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

[syzbot <syzbot+97b4444a5bd7bf30b3a8@syzkaller.appspotmail.com>]

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
=====================================================


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