[syzbot] KASAN: slab-out-of-bounds Write in dbgfs_rm_context_write

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syzbot

unread,
Oct 30, 2022, 9:44:37 PM10/30/22
to ak...@linux-foundation.org, da...@lists.linux.dev, linux-...@vger.kernel.org, linu...@kvack.org, s...@kernel.org, syzkall...@googlegroups.com
Hello,

syzbot found the following issue on:

HEAD commit: 98555239e4c3 Merge tag 'arc-6.1-fixes' of git://git.kernel..
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=12508922880000
kernel config: https://syzkaller.appspot.com/x/.config?x=a66c6c673fb555e8
dashboard link: https://syzkaller.appspot.com/bug?extid=6087eafb76a94c4ac9eb
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=167e3f4a880000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1262cb86880000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/b9ab8f713204/disk-98555239.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/5efa1b178038/vmlinux-98555239.xz
kernel image: https://storage.googleapis.com/syzbot-assets/83329b87f1a8/bzImage-98555239.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+6087ea...@syzkaller.appspotmail.com

general protection fault, probably for non-canonical address 0xdffffc0000000002: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017]
CPU: 1 PID: 3603 Comm: syz-executor414 Not tainted 6.1.0-rc2-syzkaller-00078-g98555239e4c3 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/11/2022
RIP: 0010:dbgfs_rm_context mm/damon/dbgfs.c:928 [inline]
RIP: 0010:dbgfs_rm_context_write+0x2e3/0x4d0 mm/damon/dbgfs.c:971
Code: 00 4d 8b 36 4c 39 34 24 0f 84 e4 00 00 00 e8 34 c3 a7 ff 48 8b 44 24 18 49 63 d4 48 c1 e2 03 48 8d 34 10 48 89 f7 48 c1 ef 03 <80> 3c 2f 00 0f 85 6b 01 00 00 48 8b 05 2c 85 52 0f 4c 89 36 41 83
RSP: 0018:ffffc90003d3fcb0 EFLAGS: 00010202
RAX: 0000000000000010 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000010 RDI: 0000000000000002
RBP: dffffc0000000000 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000000
R13: ffff88806f180000 R14: ffff88801b67a468 R15: 0000000000000000
FS: 00005555559df300(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000002000f000 CR3: 000000007e9a6000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
full_proxy_write+0x118/0x180 fs/debugfs/file.c:236
vfs_write+0x2d7/0xdd0 fs/read_write.c:582
ksys_write+0x127/0x250 fs/read_write.c:637
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f4ee923dd69
Code: 28 c3 e8 2a 14 00 00 66 2e 0f 1f 84 00 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffd47563a18 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f4ee923dd69
RDX: 000000000000fe6c RSI: 0000000020000080 RDI: 0000000000000003
RBP: 00007f4ee9201f10 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f4ee9201fa0
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:dbgfs_rm_context mm/damon/dbgfs.c:928 [inline]
RIP: 0010:dbgfs_rm_context_write+0x2e3/0x4d0 mm/damon/dbgfs.c:971
Code: 00 4d 8b 36 4c 39 34 24 0f 84 e4 00 00 00 e8 34 c3 a7 ff 48 8b 44 24 18 49 63 d4 48 c1 e2 03 48 8d 34 10 48 89 f7 48 c1 ef 03 <80> 3c 2f 00 0f 85 6b 01 00 00 48 8b 05 2c 85 52 0f 4c 89 36 41 83
RSP: 0018:ffffc90003d3fcb0 EFLAGS: 00010202
RAX: 0000000000000010 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000010 RDI: 0000000000000002
RBP: dffffc0000000000 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000000
R13: ffff88806f180000 R14: ffff88801b67a468 R15: 0000000000000000
FS: 00005555559df300(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000561931b2a098 CR3: 000000007e9a6000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 00 4d 8b add %cl,-0x75(%rbp)
3: 36 4c 39 34 24 cmp %r14,%ss:(%rsp)
8: 0f 84 e4 00 00 00 je 0xf2
e: e8 34 c3 a7 ff callq 0xffa7c347
13: 48 8b 44 24 18 mov 0x18(%rsp),%rax
18: 49 63 d4 movslq %r12d,%rdx
1b: 48 c1 e2 03 shl $0x3,%rdx
1f: 48 8d 34 10 lea (%rax,%rdx,1),%rsi
23: 48 89 f7 mov %rsi,%rdi
26: 48 c1 ef 03 shr $0x3,%rdi
* 2a: 80 3c 2f 00 cmpb $0x0,(%rdi,%rbp,1) <-- trapping instruction
2e: 0f 85 6b 01 00 00 jne 0x19f
34: 48 8b 05 2c 85 52 0f mov 0xf52852c(%rip),%rax # 0xf528567
3b: 4c 89 36 mov %r14,(%rsi)
3e: 41 rex.B
3f: 83 .byte 0x83


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
syzbot can test patches for this issue, for details see:
https://goo.gl/tpsmEJ#testing-patches

Hillf Danton

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Oct 31, 2022, 12:43:21 AM10/31/22
to syzbot, linux-...@vger.kernel.org, syzkall...@googlegroups.com
On 30 Oct 2022 18:44:35 -0700
> syzbot found the following issue on:
>
> HEAD commit: 98555239e4c3 Merge tag 'arc-6.1-fixes' of git://git.kernel..
> git tree: upstream
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=12508922880000
> kernel config: https://syzkaller.appspot.com/x/.config?x=a66c6c673fb555e8
> dashboard link: https://syzkaller.appspot.com/bug?extid=6087eafb76a94c4ac9eb
> compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=167e3f4a880000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1262cb86880000

Add debug info.

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 98555239e4c3

--- x/mm/damon/dbgfs.c
+++ d/mm/damon/dbgfs.c
@@ -925,6 +925,7 @@ static int dbgfs_rm_context(char *name)
dbgfs_destroy_ctx(dbgfs_ctxs[i]);
continue;
}
+ WARN_ON_ONCE(dbgfs_nr_ctxs - 1 == j);
new_dirs[j] = dbgfs_dirs[i];
new_ctxs[j++] = dbgfs_ctxs[i];
}
--

syzbot

unread,
Oct 31, 2022, 1:29:24 AM10/31/22
to hda...@sina.com, linux-...@vger.kernel.org, syzkall...@googlegroups.com
Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
WARNING in dbgfs_rm_context_write

------------[ cut here ]------------
WARNING: CPU: 0 PID: 4167 at mm/damon/dbgfs.c:928 dbgfs_rm_context mm/damon/dbgfs.c:928 [inline]
WARNING: CPU: 0 PID: 4167 at mm/damon/dbgfs.c:928 dbgfs_rm_context_write+0x40a/0x4d0 mm/damon/dbgfs.c:972
Modules linked in:
CPU: 0 PID: 4167 Comm: syz-executor.0 Not tainted 6.1.0-rc2-syzkaller-00078-g98555239e4c3-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/11/2022
RIP: 0010:dbgfs_rm_context mm/damon/dbgfs.c:928 [inline]
RIP: 0010:dbgfs_rm_context_write+0x40a/0x4d0 mm/damon/dbgfs.c:972
Code: 03 42 80 3c 30 00 0f 85 d6 00 00 00 48 8b 3b e8 4c 19 ff ff 48 8b 05 a5 83 52 0f 48 89 44 24 08 e9 40 ff ff ff e8 f6 c1 a7 ff <0f> 0b e9 d0 fe ff ff e8 ea c1 a7 ff 48 8b 3c 24 49 c7 c5 f4 ff ff
RSP: 0018:ffffc900049bfcb0 EFLAGS: 00010293
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: ffff8880745d0000 RSI: ffffffff81d4da8a RDI: 0000000000000004
RBP: 0000000000000000 R08: 0000000000000004 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000000
R13: 0000000000000000 R14: dffffc0000000000 R15: ffff888144cb2000
FS: 00007f5b5b5ac700(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000002000f000 CR3: 000000006f407000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
full_proxy_write+0x118/0x180 fs/debugfs/file.c:236
vfs_write+0x2d7/0xdd0 fs/read_write.c:582
ksys_write+0x127/0x250 fs/read_write.c:637
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f5b5a88b5a9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f5b5b5ac168 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f5b5a9abf80 RCX: 00007f5b5a88b5a9
RDX: 000000000000fe6c RSI: 0000000020000080 RDI: 0000000000000003
RBP: 00007f5b5a8e67b0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffe981eb0df R14: 00007f5b5b5ac300 R15: 0000000000022000
</TASK>


Tested on:

commit: 98555239 Merge tag 'arc-6.1-fixes' of git://git.kernel..
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=1258d3ce880000
kernel config: https://syzkaller.appspot.com/x/.config?x=a66c6c673fb555e8
dashboard link: https://syzkaller.appspot.com/bug?extid=6087eafb76a94c4ac9eb
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
patch: https://syzkaller.appspot.com/x/patch.diff?x=112688a6880000

Hillf Danton

unread,
Oct 31, 2022, 3:10:59 AM10/31/22
to syzbot, linux-...@vger.kernel.org, syzkall...@googlegroups.com
On 30 Oct 2022 18:44:35 -0700
> syzbot found the following issue on:
>
> HEAD commit: 98555239e4c3 Merge tag 'arc-6.1-fixes' of git://git.kernel..
> git tree: upstream
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=12508922880000
> kernel config: https://syzkaller.appspot.com/x/.config?x=a66c6c673fb555e8
> dashboard link: https://syzkaller.appspot.com/bug?extid=6087eafb76a94c4ac9eb
> compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=167e3f4a880000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1262cb86880000

Add debug info.

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 98555239e4c3

--- x/mm/damon/dbgfs.c
+++ d/mm/damon/dbgfs.c
@@ -905,14 +905,14 @@ static int dbgfs_rm_context(char *name)
if (!dir)
return -ENOENT;

- new_dirs = kmalloc_array(dbgfs_nr_ctxs - 1, sizeof(*dbgfs_dirs),
+ new_dirs = kmalloc_array(dbgfs_nr_ctxs, sizeof(*dbgfs_dirs),
GFP_KERNEL);
if (!new_dirs) {
ret = -ENOMEM;
goto out_dput;
}

- new_ctxs = kmalloc_array(dbgfs_nr_ctxs - 1, sizeof(*dbgfs_ctxs),
+ new_ctxs = kmalloc_array(dbgfs_nr_ctxs, sizeof(*dbgfs_ctxs),
GFP_KERNEL);
if (!new_ctxs) {
ret = -ENOMEM;
--

syzbot

unread,
Oct 31, 2022, 9:54:30 AM10/31/22
to hda...@sina.com, linux-...@vger.kernel.org, syzkall...@googlegroups.com
Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
general protection fault in dbgfs_rm_context_write

general protection fault, probably for non-canonical address 0xdffffc0000000002: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017]
CPU: 1 PID: 4159 Comm: syz-executor.0 Not tainted 6.1.0-rc2-syzkaller-00078-g98555239e4c3-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/11/2022
RIP: 0010:dbgfs_rm_context mm/damon/dbgfs.c:900 [inline]
RIP: 0010:dbgfs_rm_context_write+0x155/0x4c0 mm/damon/dbgfs.c:971
Code: a1 c1 a7 ff 45 85 e4 0f 85 ca 02 00 00 e8 c3 c4 a7 ff 48 8b 1d 5c 86 52 0f 48 b8 00 00 00 00 00 fc ff df 48 89 da 48 c1 ea 03 <80> 3c 02 00 0f 85 1f 03 00 00 48 8b 2b 48 85 ed 0f 84 8e 02 00 00
RSP: 0018:ffffc9000596fcb0 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: 0000000000000010 RCX: 0000000000000000
RDX: 0000000000000002 RSI: ffffffff81d4d7bd RDI: 0000000000000005
RBP: 0000000020000040 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000000 R11: 000000000008c07e R12: 0000000000000000
R13: ffff88806d41a000 R14: ffffc9000596fec8 R15: ffffffffffffffea
FS: 00007f469e46e700(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f469d7a80c0 CR3: 000000007ebb7000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
full_proxy_write+0x118/0x180 fs/debugfs/file.c:236
vfs_write+0x2d7/0xdd0 fs/read_write.c:582
ksys_write+0x127/0x250 fs/read_write.c:637
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f469d68b5a9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f469e46e168 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f469d7abf80 RCX: 00007f469d68b5a9
RDX: 0000000000000188 RSI: 0000000020000040 RDI: 0000000000000003
RBP: 00007f469d6e67b0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fffab8c608f R14: 00007f469e46e300 R15: 0000000000022000
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:dbgfs_rm_context mm/damon/dbgfs.c:900 [inline]
RIP: 0010:dbgfs_rm_context_write+0x155/0x4c0 mm/damon/dbgfs.c:971
Code: a1 c1 a7 ff 45 85 e4 0f 85 ca 02 00 00 e8 c3 c4 a7 ff 48 8b 1d 5c 86 52 0f 48 b8 00 00 00 00 00 fc ff df 48 89 da 48 c1 ea 03 <80> 3c 02 00 0f 85 1f 03 00 00 48 8b 2b 48 85 ed 0f 84 8e 02 00 00
RSP: 0018:ffffc9000596fcb0 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: 0000000000000010 RCX: 0000000000000000
RDX: 0000000000000002 RSI: ffffffff81d4d7bd RDI: 0000000000000005
RBP: 0000000020000040 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000000 R11: 000000000008c07e R12: 0000000000000000
R13: ffff88806d41a000 R14: ffffc9000596fec8 R15: ffffffffffffffea
FS: 00007f469e46e700(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f469e44d718 CR3: 000000007ebb7000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess), 4 bytes skipped:
0: 45 85 e4 test %r12d,%r12d
3: 0f 85 ca 02 00 00 jne 0x2d3
9: e8 c3 c4 a7 ff callq 0xffa7c4d1
e: 48 8b 1d 5c 86 52 0f mov 0xf52865c(%rip),%rbx # 0xf528671
15: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax
1c: fc ff df
1f: 48 89 da mov %rbx,%rdx
22: 48 c1 ea 03 shr $0x3,%rdx
* 26: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1) <-- trapping instruction
2a: 0f 85 1f 03 00 00 jne 0x34f
30: 48 8b 2b mov (%rbx),%rbp
33: 48 85 ed test %rbp,%rbp
36: 0f 84 8e 02 00 00 je 0x2ca


Tested on:

commit: 98555239 Merge tag 'arc-6.1-fixes' of git://git.kernel..
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=12222096880000
kernel config: https://syzkaller.appspot.com/x/.config?x=a66c6c673fb555e8
dashboard link: https://syzkaller.appspot.com/bug?extid=6087eafb76a94c4ac9eb
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
patch: https://syzkaller.appspot.com/x/patch.diff?x=15f025ce880000

SeongJae Park

unread,
Oct 31, 2022, 2:30:34 PM10/31/22
to syzbot, ak...@linux-foundation.org, da...@lists.linux.dev, linux-...@vger.kernel.org, linu...@kvack.org, s...@kernel.org, syzkall...@googlegroups.com
Hello,

On Sun, 30 Oct 2022 18:44:35 -0700 syzbot <syzbot+6087ea...@syzkaller.appspotmail.com> wrote:

> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: 98555239e4c3 Merge tag 'arc-6.1-fixes' of git://git.kernel..
> git tree: upstream
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=12508922880000
> kernel config: https://syzkaller.appspot.com/x/.config?x=a66c6c673fb555e8
> dashboard link: https://syzkaller.appspot.com/bug?extid=6087eafb76a94c4ac9eb
> compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=167e3f4a880000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1262cb86880000
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/b9ab8f713204/disk-98555239.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/5efa1b178038/vmlinux-98555239.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/83329b87f1a8/bzImage-98555239.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+6087ea...@syzkaller.appspotmail.com
>
> general protection fault, probably for non-canonical address 0xdffffc0000000002: 0000 [#1] PREEMPT SMP KASAN
> KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017]
> CPU: 1 PID: 3603 Comm: syz-executor414 Not tainted 6.1.0-rc2-syzkaller-00078-g98555239e4c3 #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/11/2022
> RIP: 0010:dbgfs_rm_context mm/damon/dbgfs.c:928 [inline]
> RIP: 0010:dbgfs_rm_context_write+0x2e3/0x4d0 mm/damon/dbgfs.c:971

Thank you for this report. I just posted a patchset[1] for the fix and
selftest repro of this bug.

[1] https://lore.kernel.org/damon/202210311825...@kernel.org/

Thanks,
SJ

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