[syzbot] [net?] general protection fault in put_page (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: f9f24ca362a4 Add linux-next specific files for 20241031
git tree: linux-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=131f2630580000
kernel config: https://syzkaller.appspot.com/x/.config?x=328572ed4d152be9
dashboard link: https://syzkaller.appspot.com/bug?extid=71abe7ab2b70bca770fd
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1110d2a7980000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=153e5540580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/eb84549dd6b3/disk-f9f24ca3.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/beb29bdfa297/vmlinux-f9f24ca3.xz
kernel image: https://storage.googleapis.com/syzbot-assets/8881fe3245ad/bzImage-f9f24ca3.xz

The issue was bisected to:

commit e4e535bff2bc82bb49a633775f9834beeaa527db
Author: Ming Lei <ming...@redhat.com>
Date: Thu Oct 24 05:00:15 2024 +0000

iov_iter: don't require contiguous pages in iov_iter_extract_bvec_pages

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1539b2a7980000
console output: https://syzkaller.appspot.com/x/log.txt?x=1339b2a7980000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+71abe7...@syzkaller.appspotmail.com
Fixes: e4e535bff2bc ("iov_iter: don't require contiguous pages in iov_iter_extract_bvec_pages")

Oops: general protection fault, probably for non-canonical address 0xed2e87ee8f0cadc6: 0000 [#1] PREEMPT SMP KASAN PTI
KASAN: maybe wild-memory-access in range [0x69745f7478656e30-0x69745f7478656e37]
CPU: 1 UID: 0 PID: 5869 Comm: syz-executor171 Not tainted 6.12.0-rc5-next-20241031-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
RIP: 0010:_compound_head include/linux/page-flags.h:242 [inline]
RIP: 0010:put_page+0x23/0x260 include/linux/mm.h:1552
Code: 90 90 90 90 90 90 90 55 41 57 41 56 53 49 89 fe 48 bd 00 00 00 00 00 fc ff df e8 d8 ae 0d f8 49 8d 5e 08 48 89 d8 48 c1 e8 03 <80> 3c 28 00 74 08 48 89 df e8 5f e5 77 f8 48 8b 1b 48 89 de 48 83
RSP: 0018:ffffc90003f970a8 EFLAGS: 00010207
RAX: 0d2e8bee8f0cadc6 RBX: 69745f7478656e36 RCX: ffff8880306d3c00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 69745f7478656e2e
RBP: dffffc0000000000 R08: ffffffff898706fd R09: 1ffffffff203a076
R10: dffffc0000000000 R11: fffffbfff203a077 R12: 0000000000000000
R13: ffff88807fd7a842 R14: 69745f7478656e2e R15: 69745f7478656e2e
FS: 0000555590726380(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000045ad50 CR3: 0000000025350000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
skb_page_unref include/linux/skbuff_ref.h:43 [inline]
__skb_frag_unref include/linux/skbuff_ref.h:56 [inline]
skb_release_data+0x483/0x8a0 net/core/skbuff.c:1119
skb_release_all net/core/skbuff.c:1190 [inline]
__kfree_skb net/core/skbuff.c:1204 [inline]
sk_skb_reason_drop+0x1c9/0x380 net/core/skbuff.c:1242
kfree_skb_reason include/linux/skbuff.h:1262 [inline]
kfree_skb include/linux/skbuff.h:1271 [inline]
__ip_flush_pending_frames net/ipv4/ip_output.c:1538 [inline]
ip_flush_pending_frames+0x12d/0x260 net/ipv4/ip_output.c:1545
udp_flush_pending_frames net/ipv4/udp.c:829 [inline]
udp_sendmsg+0x5d2/0x2a50 net/ipv4/udp.c:1302
sock_sendmsg_nosec net/socket.c:729 [inline]
__sock_sendmsg+0x1a6/0x270 net/socket.c:744
sock_sendmsg+0x134/0x200 net/socket.c:767
splice_to_socket+0xa10/0x10b0 fs/splice.c:889
do_splice_from fs/splice.c:941 [inline]
direct_splice_actor+0x11b/0x220 fs/splice.c:1164
splice_direct_to_actor+0x586/0xc80 fs/splice.c:1108
do_splice_direct_actor fs/splice.c:1207 [inline]
do_splice_direct+0x289/0x3e0 fs/splice.c:1233
do_sendfile+0x561/0xe10 fs/read_write.c:1388
__do_sys_sendfile64 fs/read_write.c:1455 [inline]
__se_sys_sendfile64+0x17c/0x1e0 fs/read_write.c:1441
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f17eb533ab9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 c1 17 00 00 90 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:00007ffdeb190c28 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f17eb533ab9
RDX: 0000000000000000 RSI: 0000000000000003 RDI: 0000000000000004
RBP: 00007f17eb5a65f0 R08: 0000000000000006 R09: 0000000000000006
R10: 0000020000023893 R11: 0000000000000246 R12: 0000000000000001
R13: 431bde82d7b634db R14: 0000000000000001 R15: 0000000000000001
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:_compound_head include/linux/page-flags.h:242 [inline]
RIP: 0010:put_page+0x23/0x260 include/linux/mm.h:1552
Code: 90 90 90 90 90 90 90 55 41 57 41 56 53 49 89 fe 48 bd 00 00 00 00 00 fc ff df e8 d8 ae 0d f8 49 8d 5e 08 48 89 d8 48 c1 e8 03 <80> 3c 28 00 74 08 48 89 df e8 5f e5 77 f8 48 8b 1b 48 89 de 48 83
RSP: 0018:ffffc90003f970a8 EFLAGS: 00010207
RAX: 0d2e8bee8f0cadc6 RBX: 69745f7478656e36 RCX: ffff8880306d3c00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 69745f7478656e2e
RBP: dffffc0000000000 R08: ffffffff898706fd R09: 1ffffffff203a076
R10: dffffc0000000000 R11: fffffbfff203a077 R12: 0000000000000000
R13: ffff88807fd7a842 R14: 69745f7478656e2e R15: 69745f7478656e2e
FS: 0000555590726380(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000045ad50 CR3: 0000000025350000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 90 nop
1: 90 nop
2: 90 nop
3: 90 nop
4: 90 nop
5: 90 nop
6: 90 nop
7: 55 push %rbp
8: 41 57 push %r15
a: 41 56 push %r14
c: 53 push %rbx
d: 49 89 fe mov %rdi,%r14
10: 48 bd 00 00 00 00 00 movabs $0xdffffc0000000000,%rbp
17: fc ff df
1a: e8 d8 ae 0d f8 call 0xf80daef7
1f: 49 8d 5e 08 lea 0x8(%r14),%rbx
23: 48 89 d8 mov %rbx,%rax
26: 48 c1 e8 03 shr $0x3,%rax
* 2a: 80 3c 28 00 cmpb $0x0,(%rax,%rbp,1) <-- trapping instruction
2e: 74 08 je 0x38
30: 48 89 df mov %rbx,%rdi
33: e8 5f e5 77 f8 call 0xf877e597
38: 48 8b 1b mov (%rbx),%rbx
3b: 48 89 de mov %rbx,%rsi
3e: 48 rex.W
3f: 83 .byte 0x83


---
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For information about bisection process see: https://goo.gl/tpsmEJ#bisection

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

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[Hillf Danton]

On Fri, 01 Nov 2024 10:44:24 -0700

> syzbot found the following issue on:
>
> HEAD commit: f9f24ca362a4 Add linux-next specific files for 20241031
> git tree: linux-next

> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=153e5540580000

#syz test

--- x/lib/iov_iter.c
+++ y/lib/iov_iter.c
@@ -1727,6 +1727,10 @@ static ssize_t iov_iter_extract_bvec_pag

(*pages)[k++] = bv.bv_page;
size += bv.bv_len;
+ if (size > maxsize) {
+ size = maxsize;
+ break;
+ }

if (k >= maxpages)
break;
--

[Ming Lei]

#syz test: https://github.com/ming1/linux.git for-next

Thanks,
Ming

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+71abe7...@syzkaller.appspotmail.com
Tested-by: syzbot+71abe7...@syzkaller.appspotmail.com

Tested on:

commit: c88416ba Add linux-next specific files for 20241101
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=1607d340580000
kernel config: https://syzkaller.appspot.com/x/.config?x=3ebcda5c61915e91

dashboard link: https://syzkaller.appspot.com/bug?extid=71abe7ab2b70bca770fd
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

patch: https://syzkaller.appspot.com/x/patch.diff?x=1368f2a7980000

Note: testing is done by a robot and is best-effort only.

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+71abe7...@syzkaller.appspotmail.com
Tested-by: syzbot+71abe7...@syzkaller.appspotmail.com

Tested on:

commit: f7270670 lib/iov_iter.c: fix iov_iter_extract_bvec_pages
git tree: https://github.com/ming1/linux.git for-next
console output: https://syzkaller.appspot.com/x/log.txt?x=12849630580000
kernel config: https://syzkaller.appspot.com/x/.config?x=3ebcda5c61915e91

dashboard link: https://syzkaller.appspot.com/bug?extid=71abe7ab2b70bca770fd
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

Note: no patches were applied.