[syzbot] [crypto?] KMSAN: uninit-value in skcipher_walk_virt

[syzbot] [crypto?] KMSAN: uninit-value in skcipher_walk_virt

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    f03359bca01b Merge tag 'for-6.9-rc6-tag' of git://git.kern..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17c169df180000
kernel config:  https://syzkaller.appspot.com/x/.config?x=bbf567496022057b
dashboard link: https://syzkaller.appspot.com/bug?extid=97b4444a5bd7bf30b3a8
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: i386

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/b345b1c01095/disk-f03359bc.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d59970ea319e/vmlinux-f03359bc.xz
kernel image: https://storage.googleapis.com/syzbot-assets/47407f406f40/bzImage-f03359bc.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+97b4444a5bd7bf30b3a8@syzkaller.appspotmail.com

loop3: detected capacity change from 0 to 32768
bcachefs (loop3): mounting version 1.7: mi_btree_bitmap opts=metadata_checksum=none,data_checksum=none,nojournal_transaction_names
bcachefs (loop3): recovering from clean shutdown, journal seq 10
=====================================================
BUG: KMSAN: uninit-value in skcipher_walk_virt+0x91/0x1a0 crypto/skcipher.c:504
 skcipher_walk_virt+0x91/0x1a0 crypto/skcipher.c:504
 chacha_stream_xor+0x7c/0x710 crypto/chacha_generic.c:22
 crypto_chacha_crypt+0x79/0xb0 crypto/chacha_generic.c:45
 crypto_skcipher_encrypt+0x1a0/0x1e0 crypto/skcipher.c:671
 do_encrypt_sg fs/bcachefs/checksum.c:107 [inline]
 do_encrypt+0x99c/0xc30 fs/bcachefs/checksum.c:127
 gen_poly_key fs/bcachefs/checksum.c:190 [inline]
 bch2_checksum+0x21f/0x7c0 fs/bcachefs/checksum.c:226
 bch2_btree_node_read_done+0x1898/0x75e0 fs/bcachefs/btree_io.c:1055
 btree_node_read_work+0x8a5/0x1eb0 fs/bcachefs/btree_io.c:1324
 bch2_btree_node_read+0x3d42/0x4b50
 __bch2_btree_root_read fs/bcachefs/btree_io.c:1748 [inline]
 bch2_btree_root_read+0xa6c/0x13d0 fs/bcachefs/btree_io.c:1772
 read_btree_roots+0x454/0xee0 fs/bcachefs/recovery.c:457
 bch2_fs_recovery+0x7adb/0x9310 fs/bcachefs/recovery.c:785
 bch2_fs_start+0x7b2/0xbd0 fs/bcachefs/super.c:1043
 bch2_fs_open+0x135f/0x1670 fs/bcachefs/super.c:2102
 bch2_mount+0x90d/0x1d90 fs/bcachefs/fs.c:1903
 legacy_get_tree+0x114/0x290 fs/fs_context.c:662
 vfs_get_tree+0xa7/0x570 fs/super.c:1779
 do_new_mount+0x71f/0x15e0 fs/namespace.c:3352
 path_mount+0x742/0x1f20 fs/namespace.c:3679
 do_mount fs/namespace.c:3692 [inline]
 __do_sys_mount fs/namespace.c:3898 [inline]
 __se_sys_mount+0x725/0x810 fs/namespace.c:3875
 __ia32_sys_mount+0xe3/0x150 fs/namespace.c:3875
 ia32_sys_call+0x3a9a/0x40a0 arch/x86/include/generated/asm/syscalls_32.h:22
 do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
 __do_fast_syscall_32+0xb4/0x120 arch/x86/entry/common.c:386
 do_fast_syscall_32+0x38/0x80 arch/x86/entry/common.c:411
 do_SYSENTER_32+0x1f/0x30 arch/x86/entry/common.c:449
 entry_SYSENTER_compat_after_hwframe+0x84/0x8e

Local variable __req_desc.i created at:
 do_encrypt_sg fs/bcachefs/checksum.c:101 [inline]
 do_encrypt+0x8f9/0xc30 fs/bcachefs/checksum.c:127
 gen_poly_key fs/bcachefs/checksum.c:190 [inline]
 bch2_checksum+0x21f/0x7c0 fs/bcachefs/checksum.c:226

CPU: 1 PID: 15218 Comm: syz-executor.3 Not tainted 6.9.0-rc6-syzkaller-00131-gf03359bca01b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
=====================================================


---
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 syzkaller@googlegroups.com.

syzbot will keep track of this issue. See:
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If the report is already addressed, let syzbot know by replying with:
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If you want to overwrite report's subsystems, reply with:
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(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
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If you want to undo deduplication, reply with:
#syz undup

Re: [syzbot] [crypto?] KMSAN: uninit-value in skcipher_walk_virt

[Aleksandr Nogikh]

#syz set subsystems: bcachefs

On Fri, May 3, 2024 at 2:24 PM syzbot
<syzbot+97b4444a5bd7bf30b3a8@syzkaller.appspotmail.com> wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit:    f03359bca01b Merge tag 'for-6.9-rc6-tag' of git://git.kern..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=17c169df180000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=bbf567496022057b
> dashboard link: https://syzkaller.appspot.com/bug?extid=97b4444a5bd7bf30b3a8
> compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
> userspace arch: i386
>
> Unfortunately, I don't have any reproducer for this issue yet.
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/b345b1c01095/disk-f03359bc.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/d59970ea319e/vmlinux-f03359bc.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/47407f406f40/bzImage-f03359bc.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+97b4444a5bd7bf30b3a8@syzkaller.appspotmail.com
>
> loop3: detected capacity change from 0 to 32768
> bcachefs (loop3): mounting version 1.7: mi_btree_bitmap opts=metadata_checksum=none,data_checksum=none,nojournal_transaction_names
> bcachefs (loop3): recovering from clean shutdown, journal seq 10
> =====================================================
> BUG: KMSAN: uninit-value in skcipher_walk_virt+0x91/0x1a0 crypto/skcipher.c:504
>  skcipher_walk_virt+0x91/0x1a0 crypto/skcipher.c:504
>  chacha_stream_xor+0x7c/0x710 crypto/chacha_generic.c:22
>  crypto_chacha_crypt+0x79/0xb0 crypto/chacha_generic.c:45
>  crypto_skcipher_encrypt+0x1a0/0x1e0 crypto/skcipher.c:671
>  do_encrypt_sg fs/bcachefs/checksum.c:107 [inline]
>  do_encrypt+0x99c/0xc30 fs/bcachefs/checksum.c:127
>  gen_poly_key fs/bcachefs/checksum.c:190 [inline]
>  bch2_checksum+0x21f/0x7c0 fs/bcachefs/checksum.c:226
>  bch2_btree_node_read_done+0x1898/0x75e0 fs/bcachefs/btree_io.c:1055
>  btree_node_read_work+0x8a5/0x1eb0 fs/bcachefs/btree_io.c:1324
>  bch2_btree_node_read+0x3d42/0x4b50
>  __bch2_btree_root_read fs/bcachefs/btree_io.c:1748 [inline]
>  bch2_btree_root_read+0xa6c/0x13d0 fs/bcachefs/btree_io.c:1772
>  read_btree_roots+0x454/0xee0 fs/bcachefs/recovery.c:457
>  bch2_fs_recovery+0x7adb/0x9310 fs/bcachefs/recovery.c:785
>  bch2_fs_start+0x7b2/0xbd0 fs/bcachefs/super.c:1043
>  bch2_fs_open+0x135f/0x1670 fs/bcachefs/super.c:2102
>  bch2_mount+0x90d/0x1d90 fs/bcachefs/fs.c:1903
>  legacy_get_tree+0x114/0x290 fs/fs_context.c:662
>  vfs_get_tree+0xa7/0x570 fs/super.c:1779
>  do_new_mount+0x71f/0x15e0 fs/namespace.c:3352
>  path_mount+0x742/0x1f20 fs/namespace.c:3679
>  do_mount fs/namespace.c:3692 [inline]
>  __do_sys_mount fs/namespace.c:3898 [inline]
>  __se_sys_mount+0x725/0x810 fs/namespace.c:3875
>  __ia32_sys_mount+0xe3/0x150 fs/namespace.c:3875
>  ia32_sys_call+0x3a9a/0x40a0 arch/x86/include/generated/asm/syscalls_32.h:22
>  do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
>  __do_fast_syscall_32+0xb4/0x120 arch/x86/entry/common.c:386
>  do_fast_syscall_32+0x38/0x80 arch/x86/entry/common.c:411
>  do_SYSENTER_32+0x1f/0x30 arch/x86/entry/common.c:449
>  entry_SYSENTER_compat_after_hwframe+0x84/0x8e
>
> Local variable __req_desc.i created at:
>  do_encrypt_sg fs/bcachefs/checksum.c:101 [inline]
>  do_encrypt+0x8f9/0xc30 fs/bcachefs/checksum.c:127
>  gen_poly_key fs/bcachefs/checksum.c:190 [inline]
>  bch2_checksum+0x21f/0x7c0 fs/bcachefs/checksum.c:226
>
> CPU: 1 PID: 15218 Comm: syz-executor.3 Not tainted 6.9.0-rc6-syzkaller-00131-gf03359bca01b #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
> =====================================================
>
>
> ---
> 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 syzkaller@googlegroups.com.
>
> syzbot will keep track of this issue. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
>
> If the report is already addressed, let syzbot know by replying with:
> #syz fix: exact-commit-title
>
> If you want to overwrite report's subsystems, reply with:
> #syz set subsystems: new-subsystem
> (See the list of subsystem names on the web dashboard)
>
> If the report is a duplicate of another one, reply with:
> #syz dup: exact-subject-of-another-report
>
> If you want to undo deduplication, reply with:
> #syz undup
>
> --
> You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller-bugs+unsubscribe@googlegroups.com.
> To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/000000000000dcd2ae06178bccb0%40google.com.

Re: [syzbot] [crypto?] KMSAN: uninit-value in skcipher_walk_virt

[Nikita Zhandarovich]

req->base.flags were not initialized, zero might suit in this case.
Do it with skcipher_request_set_callback() as it's common practice.

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

---
 fs/bcachefs/checksum.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/bcachefs/checksum.c b/fs/bcachefs/checksum.c
index 7ed779b411f6..088fd2e7bdf1 100644
--- a/fs/bcachefs/checksum.c
+++ b/fs/bcachefs/checksum.c
@@ -102,6 +102,7 @@ static inline int do_encrypt_sg(struct crypto_sync_skcipher *tfm,
 	int ret;
 
 	skcipher_request_set_sync_tfm(req, tfm);
+	skcipher_request_set_callback(req, 0, NULL, NULL);
 	skcipher_request_set_crypt(req, sg, sg, len, nonce.d);
 
 	ret = crypto_skcipher_encrypt(req);

Re: [syzbot] [crypto?] KMSAN: uninit-value in skcipher_walk_virt

[syzbot]

> req->base.flags were not initialized, zero might suit in this case.
> Do it with skcipher_request_set_callback() as it's common practice.
>
> #syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master

This crash does not have a reproducer. I cannot test it.

>
> ---
>  fs/bcachefs/checksum.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/fs/bcachefs/checksum.c b/fs/bcachefs/checksum.c
> index 7ed779b411f6..088fd2e7bdf1 100644
> --- a/fs/bcachefs/checksum.c
> +++ b/fs/bcachefs/checksum.c
> @@ -102,6 +102,7 @@ static inline int do_encrypt_sg(struct crypto_sync_skcipher *tfm,
>  	int ret;
>  
>  	skcipher_request_set_sync_tfm(req, tfm);
> +	skcipher_request_set_callback(req, 0, NULL, NULL);
>  	skcipher_request_set_crypt(req, sg, sg, len, nonce.d);
>  
>  	ret = crypto_skcipher_encrypt(req);

Re: [syzbot] [crypto?] KMSAN: uninit-value in skcipher_walk_virt

[Kent Overstreet]

This is odd - it seems to be req->base.flags that's uninitialized, and I
can't find the code that's supposed to be initializing it - but bcachefs
usage seems to be the same as all the other uses I'm looking at; if it
is req->base.flags then other code must be buggy as well?

On Fri, May 03, 2024 at 02:34:30PM +0200, Aleksandr Nogikh wrote:
> #syz set subsystems: bcachefs
> 
> On Fri, May 3, 2024 at 2:24 PM syzbot
> <syzbot+97b4444a5bd7bf30b3a8@syzkaller.appspotmail.com> wrote:
> >
> > Hello,
> >
> > syzbot found the following issue on:
> >
> > HEAD commit:    f03359bca01b Merge tag 'for-6.9-rc6-tag' of git://git.kern..
> > git tree:       upstream
> > console output: https://syzkaller.appspot.com/x/log.txt?x=17c169df180000
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=bbf567496022057b
> > dashboard link: https://syzkaller.appspot.com/bug?extid=97b4444a5bd7bf30b3a8
> > compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
> > userspace arch: i386
> >
> > Unfortunately, I don't have any reproducer for this issue yet.
> >
> > Downloadable assets:
> > disk image: https://storage.googleapis.com/syzbot-assets/b345b1c01095/disk-f03359bc.raw.xz
> > vmlinux: https://storage.googleapis.com/syzbot-assets/d59970ea319e/vmlinux-f03359bc.xz
> > kernel image: https://storage.googleapis.com/syzbot-assets/47407f406f40/bzImage-f03359bc.xz
> >
> > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > Reported-by: syzbot+97b4444a5bd7bf30b3a8@syzkaller.appspotmail.com
> >
> > loop3: detected capacity change from 0 to 32768
> > bcachefs (loop3): mounting version 1.7: mi_btree_bitmap opts=metadata_checksum=none,data_checksum=none,nojournal_transaction_names
> > bcachefs (loop3): recovering from clean shutdown, journal seq 10
> > =====================================================
> > BUG: KMSAN: uninit-value in skcipher_walk_virt+0x91/0x1a0 crypto/skcipher.c:504
> >  skcipher_walk_virt+0x91/0x1a0 crypto/skcipher.c:504
> >  chacha_stream_xor+0x7c/0x710 crypto/chacha_generic.c:22
> >  crypto_chacha_crypt+0x79/0xb0 crypto/chacha_generic.c:45
> >  crypto_skcipher_encrypt+0x1a0/0x1e0 crypto/skcipher.c:671
> >  do_encrypt_sg fs/bcachefs/checksum.c:107 [inline]
> >  do_encrypt+0x99c/0xc30 fs/bcachefs/checksum.c:127
> >  gen_poly_key fs/bcachefs/checksum.c:190 [inline]
> >  bch2_checksum+0x21f/0x7c0 fs/bcachefs/checksum.c:226
> >  bch2_btree_node_read_done+0x1898/0x75e0 fs/bcachefs/btree_io.c:1055
> >  btree_node_read_work+0x8a5/0x1eb0 fs/bcachefs/btree_io.c:1324
> >  bch2_btree_node_read+0x3d42/0x4b50
> >  __bch2_btree_root_read fs/bcachefs/btree_io.c:1748 [inline]
> >  bch2_btree_root_read+0xa6c/0x13d0 fs/bcachefs/btree_io.c:1772
> >  read_btree_roots+0x454/0xee0 fs/bcachefs/recovery.c:457
> >  bch2_fs_recovery+0x7adb/0x9310 fs/bcachefs/recovery.c:785
> >  bch2_fs_start+0x7b2/0xbd0 fs/bcachefs/super.c:1043
> >  bch2_fs_open+0x135f/0x1670 fs/bcachefs/super.c:2102
> >  bch2_mount+0x90d/0x1d90 fs/bcachefs/fs.c:1903
> >  legacy_get_tree+0x114/0x290 fs/fs_context.c:662
> >  vfs_get_tree+0xa7/0x570 fs/super.c:1779
> >  do_new_mount+0x71f/0x15e0 fs/namespace.c:3352
> >  path_mount+0x742/0x1f20 fs/namespace.c:3679
> >  do_mount fs/namespace.c:3692 [inline]
> >  __do_sys_mount fs/namespace.c:3898 [inline]
> >  __se_sys_mount+0x725/0x810 fs/namespace.c:3875
> >  __ia32_sys_mount+0xe3/0x150 fs/namespace.c:3875
> >  ia32_sys_call+0x3a9a/0x40a0 arch/x86/include/generated/asm/syscalls_32.h:22
> >  do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
> >  __do_fast_syscall_32+0xb4/0x120 arch/x86/entry/common.c:386
> >  do_fast_syscall_32+0x38/0x80 arch/x86/entry/common.c:411
> >  do_SYSENTER_32+0x1f/0x30 arch/x86/entry/common.c:449
> >  entry_SYSENTER_compat_after_hwframe+0x84/0x8e
> >
> > Local variable __req_desc.i created at:
> >  do_encrypt_sg fs/bcachefs/checksum.c:101 [inline]
> >  do_encrypt+0x8f9/0xc30 fs/bcachefs/checksum.c:127
> >  gen_poly_key fs/bcachefs/checksum.c:190 [inline]
> >  bch2_checksum+0x21f/0x7c0 fs/bcachefs/checksum.c:226
> >
> > CPU: 1 PID: 15218 Comm: syz-executor.3 Not tainted 6.9.0-rc6-syzkaller-00131-gf03359bca01b #0
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
> > =====================================================
> >
> >
> > ---
> > 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 syzkaller@googlegroups.com.
> >
> > syzbot will keep track of this issue. See:
> > https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> >
> > If the report is already addressed, let syzbot know by replying with:
> > #syz fix: exact-commit-title
> >
> > If you want to overwrite report's subsystems, reply with:
> > #syz set subsystems: new-subsystem
> > (See the list of subsystem names on the web dashboard)
> >
> > If the report is a duplicate of another one, reply with:
> > #syz dup: exact-subject-of-another-report
> >
> > If you want to undo deduplication, reply with:
> > #syz undup
> >
> > --
> > You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group.
> > To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller-bugs+unsubscribe@googlegroups.com.
> > To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/000000000000dcd2ae06178bccb0%40google.com.

Re: [syzbot] [crypto?] KMSAN: uninit-value in skcipher_walk_virt

[Ard Biesheuvel]

On Sat, 4 May 2024 at 19:21, Kent Overstreet <kent.overstreet@linux.dev> wrote:
>
> This is odd - it seems to be req->base.flags that's uninitialized, and I
> can't find the code that's supposed to be initializing it - but bcachefs
> usage seems to be the same as all the other uses I'm looking at; if it
> is req->base.flags then other code must be buggy as well?
>

You seem to be missing a call to

skcipher_request_set_callback()

which initializes some (irrelevant in this case) async related fields
but also the flags field.