kernel panic: smack: Failed to initialize cipso DOI.

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 1b649e0b Merge git://git.kernel.org/pub/scm/linux/kernel/g..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14957099e00000
kernel config: https://syzkaller.appspot.com/x/.config?x=4ac76c43beddbd9
dashboard link: https://syzkaller.appspot.com/bug?extid=89731ccb6fec15ce1c22
compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1202c375e00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1390bb03e00000

The bug was bisected to:

commit a9d2d53a788a9c5bc8a7d1b4ea7857b68e221357
Author: Ken Cox <j...@redhat.com>
Date: Tue Nov 15 19:00:37 2016 +0000

ixgbe: test for trust in macvlan adjustments for VF

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=13cb06f3e00000
final crash: https://syzkaller.appspot.com/x/report.txt?x=102b06f3e00000
console output: https://syzkaller.appspot.com/x/log.txt?x=17cb06f3e00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+89731c...@syzkaller.appspotmail.com
Fixes: a9d2d53a788a ("ixgbe: test for trust in macvlan adjustments for VF")

RSP: 002b:00007ffebd499a38 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007ffebd499a40 RCX: 00000000004404e9
RDX: 0000000000000014 RSI: 0000000020000040 RDI: 0000000000000003
RBP: 0000000000000004 R08: 0000000000000001 R09: 00007ffebd490031
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000401dd0
R13: 0000000000401e60 R14: 0000000000000000 R15: 0000000000000000
Kernel panic - not syncing: smack: Failed to initialize cipso DOI.
CPU: 1 PID: 7197 Comm: syz-executor480 Not tainted 5.6.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x1e9/0x30e lib/dump_stack.c:118
panic+0x264/0x7a0 kernel/panic.c:221
smk_cipso_doi+0x4d8/0x4e0 security/smack/smackfs.c:698
smk_write_doi+0x123/0x190 security/smack/smackfs.c:1595
__vfs_write+0xa7/0x710 fs/read_write.c:494
vfs_write+0x271/0x570 fs/read_write.c:558
ksys_write+0x115/0x220 fs/read_write.c:611
do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:294
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4404e9
Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 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 0f 83 5b 14 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffebd499a38 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007ffebd499a40 RCX: 00000000004404e9
RDX: 0000000000000014 RSI: 0000000020000040 RDI: 0000000000000003
RBP: 0000000000000004 R08: 0000000000000001 R09: 00007ffebd490031
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000401dd0
R13: 0000000000401e60 R14: 0000000000000000 R15: 0000000000000000
Kernel Offset: disabled
Rebooting in 86400 seconds..


---
This bug 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 bug report. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
For information about bisection process see: https://goo.gl/tpsmEJ#bisection
syzbot can test patches for this bug, for details see:
https://goo.gl/tpsmEJ#testing-patches

[Tetsuo Handa]

On 2020/03/30 22:51, syzbot wrote:
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit: 1b649e0b Merge git://git.kernel.org/pub/scm/linux/kernel/g..
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=14957099e00000
> kernel config: https://syzkaller.appspot.com/x/.config?x=4ac76c43beddbd9
> dashboard link: https://syzkaller.appspot.com/bug?extid=89731ccb6fec15ce1c22
> compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1202c375e00000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1390bb03e00000

Wrong bisection. This is not a network / driver problem.
There is a memory allocation fault injection prior to this panic.

[ T1576] FAULT_INJECTION: forcing a failure.
[ T1576] Kernel panic - not syncing: smack: Failed to initialize cipso DOI.

[Eric Biggers]

Hi Casey,

This means that writing to /smack/doi will panic the kernel if kmalloc fails.

Why doesn't it handle errors? Is this really an unrecoverable situation?

- Eric

[Tetsuo Handa]

syzbot is reporting kernel panic at smk_cipso_doi() due to memory
allocation fault injection [1]. The reason for need to use panic() was
not explained. But since no fix was proposed for 18 months, for now
let's use __GFP_NOFAIL for utilizing syzbot resource on other bugs.

Link: https://syzkaller.appspot.com/bug?extid=89731ccb6fec15ce1c22 [1]
Reported-by: syzbot <syzbot+89731c...@syzkaller.appspotmail.com>
Signed-off-by: Tetsuo Handa <penguin...@I-love.SAKURA.ne.jp>
---
security/smack/smackfs.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/security/smack/smackfs.c b/security/smack/smackfs.c
index 83b90442f963..3e6a198dd3dd 100644
--- a/security/smack/smackfs.c
+++ b/security/smack/smackfs.c
@@ -693,9 +693,7 @@ static void smk_cipso_doi(void)
printk(KERN_WARNING "%s:%d remove rc = %d\n",
__func__, __LINE__, rc);

- doip = kmalloc(sizeof(struct cipso_v4_doi), GFP_KERNEL);
- if (doip == NULL)
- panic("smack: Failed to initialize cipso DOI.\n");
+ doip = kmalloc(sizeof(struct cipso_v4_doi), GFP_KERNEL | __GFP_NOFAIL);
doip->map.std = NULL;
doip->doi = smk_cipso_doi_value;
doip->type = CIPSO_V4_MAP_PASS;
--
2.18.4

[Casey Schaufler]

On 10/19/2021 4:54 AM, Tetsuo Handa wrote:
> syzbot is reporting kernel panic at smk_cipso_doi() due to memory
> allocation fault injection [1]. The reason for need to use panic() was
> not explained. But since no fix was proposed for 18 months, for now
> let's use __GFP_NOFAIL for utilizing syzbot resource on other bugs.
>
> Link: https://syzkaller.appspot.com/bug?extid=89731ccb6fec15ce1c22 [1]
> Reported-by: syzbot <syzbot+89731c...@syzkaller.appspotmail.com>
> Signed-off-by: Tetsuo Handa <penguin...@I-love.SAKURA.ne.jp>

Added to smack-next. Thank you.