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

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: c446fdacb10d bpf: fix register_btf_kfunc_id_set for !CONFI..
git tree: bpf-next
console output: https://syzkaller.appspot.com/x/log.txt?x=118a9404700000
kernel config: https://syzkaller.appspot.com/x/.config?x=fed7021824b74f81
dashboard link: https://syzkaller.appspot.com/bug?extid=6d70ca7438345077c549
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+6d70ca...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: slab-out-of-bounds in __skb_frag_set_page include/linux/skbuff.h:3242 [inline]
BUG: KASAN: slab-out-of-bounds in bpf_prog_test_run_xdp+0x10ac/0x1150 net/bpf/test_run.c:972
Write of size 8 at addr ffff888048c75000 by task syz-executor.5/23405

CPU: 1 PID: 23405 Comm: syz-executor.5 Not tainted 5.16.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
print_address_description.constprop.0.cold+0x8d/0x336 mm/kasan/report.c:255
__kasan_report mm/kasan/report.c:442 [inline]
kasan_report.cold+0x83/0xdf mm/kasan/report.c:459
__skb_frag_set_page include/linux/skbuff.h:3242 [inline]
bpf_prog_test_run_xdp+0x10ac/0x1150 net/bpf/test_run.c:972
bpf_prog_test_run kernel/bpf/syscall.c:3356 [inline]
__sys_bpf+0x1858/0x59a0 kernel/bpf/syscall.c:4658
__do_sys_bpf kernel/bpf/syscall.c:4744 [inline]
__se_sys_bpf kernel/bpf/syscall.c:4742 [inline]
__x64_sys_bpf+0x75/0xb0 kernel/bpf/syscall.c:4742
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+0x44/0xae
RIP: 0033:0x7f4ea30dd059
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:00007f4ea1a52168 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00007f4ea31eff60 RCX: 00007f4ea30dd059
RDX: 0000000000000048 RSI: 0000000020000000 RDI: 000000000000000a
RBP: 00007f4ea313708d R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffc8367c5af R14: 00007f4ea1a52300 R15: 0000000000022000
</TASK>

Allocated by task 23405:
kasan_save_stack+0x1e/0x50 mm/kasan/common.c:38
kasan_set_track mm/kasan/common.c:46 [inline]
set_alloc_info mm/kasan/common.c:437 [inline]
____kasan_kmalloc mm/kasan/common.c:516 [inline]
____kasan_kmalloc mm/kasan/common.c:475 [inline]
__kasan_kmalloc+0xa9/0xd0 mm/kasan/common.c:525
kmalloc include/linux/slab.h:586 [inline]
kzalloc include/linux/slab.h:715 [inline]
bpf_test_init.isra.0+0x9f/0x150 net/bpf/test_run.c:411
bpf_prog_test_run_xdp+0x2f8/0x1150 net/bpf/test_run.c:941
bpf_prog_test_run kernel/bpf/syscall.c:3356 [inline]
__sys_bpf+0x1858/0x59a0 kernel/bpf/syscall.c:4658
__do_sys_bpf kernel/bpf/syscall.c:4744 [inline]
__se_sys_bpf kernel/bpf/syscall.c:4742 [inline]
__x64_sys_bpf+0x75/0xb0 kernel/bpf/syscall.c:4742
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+0x44/0xae

The buggy address belongs to the object at ffff888048c74000
which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 0 bytes to the right of
4096-byte region [ffff888048c74000, ffff888048c75000)
The buggy address belongs to the page:
page:ffffea0001231c00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x48c70
head:ffffea0001231c00 order:3 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 dead000000000100 dead000000000122 ffff888010c42140
raw: 0000000000000000 0000000080040004 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0x1d2a20(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 1137, ts 352220884506, free_ts 345202653097
prep_new_page mm/page_alloc.c:2434 [inline]
get_page_from_freelist+0xa72/0x2f50 mm/page_alloc.c:4165
__alloc_pages+0x1b2/0x500 mm/page_alloc.c:5389
alloc_pages+0x1aa/0x310 mm/mempolicy.c:2271
alloc_slab_page mm/slub.c:1799 [inline]
allocate_slab mm/slub.c:1944 [inline]
new_slab+0x28a/0x3b0 mm/slub.c:2004
___slab_alloc+0x87c/0xe90 mm/slub.c:3018
__slab_alloc.constprop.0+0x4d/0xa0 mm/slub.c:3105
slab_alloc_node mm/slub.c:3196 [inline]
__kmalloc_node_track_caller+0x2cb/0x360 mm/slub.c:4957
kmalloc_reserve net/core/skbuff.c:354 [inline]
__alloc_skb+0xde/0x340 net/core/skbuff.c:426
alloc_skb include/linux/skbuff.h:1159 [inline]
nsim_dev_trap_skb_build drivers/net/netdevsim/dev.c:745 [inline]
nsim_dev_trap_report drivers/net/netdevsim/dev.c:802 [inline]
nsim_dev_trap_report_work+0x29a/0xbc0 drivers/net/netdevsim/dev.c:843
process_one_work+0x9ac/0x1650 kernel/workqueue.c:2307
worker_thread+0x657/0x1110 kernel/workqueue.c:2454
kthread+0x2e9/0x3a0 kernel/kthread.c:377
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1352 [inline]
free_pcp_prepare+0x374/0x870 mm/page_alloc.c:1404
free_unref_page_prepare mm/page_alloc.c:3325 [inline]
free_unref_page+0x19/0x690 mm/page_alloc.c:3404
qlink_free mm/kasan/quarantine.c:157 [inline]
qlist_free_all+0x6d/0x160 mm/kasan/quarantine.c:176
kasan_quarantine_reduce+0x180/0x200 mm/kasan/quarantine.c:283
__kasan_slab_alloc+0xa2/0xc0 mm/kasan/common.c:447
kasan_slab_alloc include/linux/kasan.h:260 [inline]
slab_post_alloc_hook mm/slab.h:732 [inline]
slab_alloc_node mm/slub.c:3230 [inline]
slab_alloc mm/slub.c:3238 [inline]
kmem_cache_alloc+0x202/0x3a0 mm/slub.c:3243
getname_flags.part.0+0x50/0x4f0 fs/namei.c:138
getname_flags include/linux/audit.h:323 [inline]
getname+0x8e/0xd0 fs/namei.c:217
do_sys_openat2+0xf5/0x4d0 fs/open.c:1208
do_sys_open fs/open.c:1230 [inline]
__do_sys_openat fs/open.c:1246 [inline]
__se_sys_openat fs/open.c:1241 [inline]
__x64_sys_openat+0x13f/0x1f0 fs/open.c:1241
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+0x44/0xae

Memory state around the buggy address:
ffff888048c74f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff888048c74f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888048c75000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
^
ffff888048c75080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff888048c75100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================


---
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]

syzbot has found a reproducer for the following issue on:

HEAD commit: dd5152ab338c Merge branch 'bpf-btf-dwarf5'
git tree: bpf-next
console output: https://syzkaller.appspot.com/x/log.txt?x=15b770dbb00000
kernel config: https://syzkaller.appspot.com/x/.config?x=b210f94c3ec14b22

dashboard link: https://syzkaller.appspot.com/bug?extid=6d70ca7438345077c549
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=10044d98700000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1613fa8fb00000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+6d70ca...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: slab-out-of-bounds in __skb_frag_set_page include/linux/skbuff.h:3242 [inline]
BUG: KASAN: slab-out-of-bounds in bpf_prog_test_run_xdp+0x10ac/0x1150 net/bpf/test_run.c:972

Write of size 8 at addr ffff88801dc53000 by task syz-executor098/3592

CPU: 1 PID: 3592 Comm: syz-executor098 Not tainted 5.16.0-syzkaller-11587-gdd5152ab338c #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
print_address_description.constprop.0.cold+0x8d/0x336 mm/kasan/report.c:255
__kasan_report mm/kasan/report.c:442 [inline]
kasan_report.cold+0x83/0xdf mm/kasan/report.c:459
__skb_frag_set_page include/linux/skbuff.h:3242 [inline]
bpf_prog_test_run_xdp+0x10ac/0x1150 net/bpf/test_run.c:972
bpf_prog_test_run kernel/bpf/syscall.c:3356 [inline]
__sys_bpf+0x1858/0x59a0 kernel/bpf/syscall.c:4658
__do_sys_bpf kernel/bpf/syscall.c:4744 [inline]
__se_sys_bpf kernel/bpf/syscall.c:4742 [inline]
__x64_sys_bpf+0x75/0xb0 kernel/bpf/syscall.c:4742
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+0x44/0xae

RIP: 0033:0x7fada7c9e229
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:00007fff58406588 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fada7c9e229

RDX: 0000000000000048 RSI: 0000000020000000 RDI: 000000000000000a

RBP: 00007fada7c62210 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fada7c622a0
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
</TASK>

Allocated by task 3592:

kasan_save_stack+0x1e/0x50 mm/kasan/common.c:38
kasan_set_track mm/kasan/common.c:46 [inline]
set_alloc_info mm/kasan/common.c:437 [inline]
____kasan_kmalloc mm/kasan/common.c:516 [inline]
____kasan_kmalloc mm/kasan/common.c:475 [inline]
__kasan_kmalloc+0xa9/0xd0 mm/kasan/common.c:525
kmalloc include/linux/slab.h:586 [inline]
kzalloc include/linux/slab.h:715 [inline]
bpf_test_init.isra.0+0x9f/0x150 net/bpf/test_run.c:411
bpf_prog_test_run_xdp+0x2f8/0x1150 net/bpf/test_run.c:941
bpf_prog_test_run kernel/bpf/syscall.c:3356 [inline]
__sys_bpf+0x1858/0x59a0 kernel/bpf/syscall.c:4658
__do_sys_bpf kernel/bpf/syscall.c:4744 [inline]
__se_sys_bpf kernel/bpf/syscall.c:4742 [inline]
__x64_sys_bpf+0x75/0xb0 kernel/bpf/syscall.c:4742
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+0x44/0xae

The buggy address belongs to the object at ffff88801dc52000

which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 0 bytes to the right of

4096-byte region [ffff88801dc52000, ffff88801dc53000)

The buggy address belongs to the page:

page:ffffea0000771400 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1dc50
head:ffffea0000771400 order:3 compound_mapcount:0 compound_pincount:0

flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)

raw: 00fff00000010200 0000000000000000 dead000000000122 ffff888010c42140

raw: 0000000000000000 0000000080040004 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated

page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 3592, ts 49734537716, free_ts 49716400399

prep_new_page mm/page_alloc.c:2434 [inline]
get_page_from_freelist+0xa72/0x2f50 mm/page_alloc.c:4165
__alloc_pages+0x1b2/0x500 mm/page_alloc.c:5389
alloc_pages+0x1aa/0x310 mm/mempolicy.c:2271
alloc_slab_page mm/slub.c:1799 [inline]
allocate_slab mm/slub.c:1944 [inline]
new_slab+0x28a/0x3b0 mm/slub.c:2004
___slab_alloc+0x87c/0xe90 mm/slub.c:3018
__slab_alloc.constprop.0+0x4d/0xa0 mm/slub.c:3105
slab_alloc_node mm/slub.c:3196 [inline]

slab_alloc mm/slub.c:3238 [inline]
kmem_cache_alloc_trace+0x289/0x2c0 mm/slub.c:3255
kmalloc include/linux/slab.h:581 [inline]
kzalloc include/linux/slab.h:715 [inline]
ima_calc_file_hash_tfm+0x282/0x3b0 security/integrity/ima/ima_crypto.c:477
ima_calc_file_shash security/integrity/ima/ima_crypto.c:515 [inline]
ima_calc_file_hash+0x19d/0x4b0 security/integrity/ima/ima_crypto.c:572
ima_collect_measurement+0x4c9/0x570 security/integrity/ima/ima_api.c:254
process_measurement+0xd37/0x1920 security/integrity/ima/ima_main.c:337
ima_bprm_check+0xd0/0x220 security/integrity/ima/ima_main.c:491
security_bprm_check+0x7d/0xa0 security/security.c:869
search_binary_handler fs/exec.c:1714 [inline]
exec_binprm fs/exec.c:1767 [inline]
bprm_execve fs/exec.c:1836 [inline]
bprm_execve+0x732/0x19b0 fs/exec.c:1798
do_execveat_common+0x5e3/0x780 fs/exec.c:1925
do_execve fs/exec.c:1993 [inline]
__do_sys_execve fs/exec.c:2069 [inline]
__se_sys_execve fs/exec.c:2064 [inline]
__x64_sys_execve+0x8f/0xc0 fs/exec.c:2064

page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1352 [inline]
free_pcp_prepare+0x374/0x870 mm/page_alloc.c:1404
free_unref_page_prepare mm/page_alloc.c:3325 [inline]
free_unref_page+0x19/0x690 mm/page_alloc.c:3404

__unfreeze_partials+0x320/0x340 mm/slub.c:2536

qlink_free mm/kasan/quarantine.c:157 [inline]
qlist_free_all+0x6d/0x160 mm/kasan/quarantine.c:176
kasan_quarantine_reduce+0x180/0x200 mm/kasan/quarantine.c:283
__kasan_slab_alloc+0xa2/0xc0 mm/kasan/common.c:447
kasan_slab_alloc include/linux/kasan.h:260 [inline]
slab_post_alloc_hook mm/slab.h:732 [inline]
slab_alloc_node mm/slub.c:3230 [inline]
slab_alloc mm/slub.c:3238 [inline]
kmem_cache_alloc+0x202/0x3a0 mm/slub.c:3243
getname_flags.part.0+0x50/0x4f0 fs/namei.c:138

getname_flags+0x9a/0xe0 include/linux/audit.h:323
user_path_at_empty+0x2b/0x60 fs/namei.c:2800
user_path_at include/linux/namei.h:57 [inline]
vfs_statx+0x142/0x390 fs/stat.c:221
vfs_fstatat fs/stat.c:243 [inline]
__do_sys_newfstatat+0x96/0x120 fs/stat.c:412

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+0x44/0xae

Memory state around the buggy address:

ffff88801dc52f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff88801dc52f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88801dc53000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
^
ffff88801dc53080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88801dc53100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================

[Alexei Starovoitov]

Lorenzo, please take a look. I suspect it's xdp frags related.

[Lorenzo Bianconi]

> Lorenzo, please take a look. I suspect it's xdp frags related.

Hi Alexei,

ack, I am looking into it.

Regards,
Lorenzo

[Lorenzo Bianconi]

#syz test: https://github.com/LorenzoBianconi/bpf-next.git skzkaller_bpf_prog_test_run_xdp

[syzbot]

Hello,

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

Reported-and-tested-by: syzbot+6d70ca...@syzkaller.appspotmail.com

Tested on:

commit: 3e274d57 bpf: test_run: fix OOB access in bpf_prog_tes..
git tree: https://github.com/LorenzoBianconi/bpf-next.git skzkaller_bpf_prog_test_run_xdp
kernel config: https://syzkaller.appspot.com/x/.config?x=b210f94c3ec14b22

dashboard link: https://syzkaller.appspot.com/bug?extid=6d70ca7438345077c549
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

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

[syzbot]

syzbot has bisected this issue to:

commit 1c194998252469cad00a08bd9ef0b99fd255c260
Author: Lorenzo Bianconi <lor...@kernel.org>
Date: Fri Jan 21 10:09:58 2022 +0000

bpf: introduce frags support to bpf_prog_test_run_xdp()

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=15a1e914700000
start commit: 000fe940e51f sfc: The size of the RX recycle ring should b..
git tree: net-next
final oops: https://syzkaller.appspot.com/x/report.txt?x=17a1e914700000
console output: https://syzkaller.appspot.com/x/log.txt?x=13a1e914700000
kernel config: https://syzkaller.appspot.com/x/.config?x=e029d3b2ccd4c91a
dashboard link: https://syzkaller.appspot.com/bug?extid=6d70ca7438345077c549
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14c08cc8700000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1258f610700000

Reported-by: syzbot+6d70ca...@syzkaller.appspotmail.com
Fixes: 1c1949982524 ("bpf: introduce frags support to bpf_prog_test_run_xdp()")

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

[Lorenzo Bianconi]

> Lorenzo, please take a look. I suspect it's xdp frags related.

Hi Alexei,

do you think it is worth to add a test for this condition in
test_xdp_update_frags()?

Regards,
Lorenzo

[Alexei Starovoitov]

On Thu, Feb 3, 2022 at 10:11 AM Lorenzo Bianconi <lor...@kernel.org> wrote:
>
> > Lorenzo, please take a look. I suspect it's xdp frags related.
>
> Hi Alexei,
>
> do you think it is worth to add a test for this condition in
> test_xdp_update_frags()?

you mean instead of 9000 and implicit PAGE_SIZE splitting
allocate explicit PAGE_SIZE * MAX_SKB_FRAGS ?
Yeah. Would be nice.