Re: kernel panic caused by recent changes in fs/cifs

[Chenglong Tang <chenglongtang@xxxxxxxxxx>]

Here is the backtrace.

On Tue, Apr 9, 2024 at 11:37 PM Chenglong Tang <chenglongtang@xxxxxxxxxx> wrote:

Hi, developers,

This is Chenglong Tang from the Google Container Optimized OS team. We recently received a kernel panic bug from the customers regarding cifs. 

This happened since the backport of following changes in cifs(in our kernel COS-5.10.208 and COS-5.15.146):

cifs: Fix non-availability of dedup breaking generic/304: https://lore.kernel.org/r/3876191.1701555260@xxxxxxxxxxxxxxxxxxxxxx/

smb: client: fix potential NULL deref in parse_dfs_referrals(): Upstream commit 92414333eb375ed64f4ae92d34d579e826936480

ksmbd: fix wrong name of SMB2_CREATE_ALLOCATION_SIZE: Upstream commit  13736654481198e519059d4a2e2e3b20fa9fdb3e

smb: client: fix NULL deref in asn1_ber_decoder(): Upstream commit 90d025c2e953c11974e76637977c473200593a46

smb: a few more smb changes...

The line that crashed is line 197 in fs/cifs/dfs_cache.c

```

if (unlikely(strcmp(cp->charset, cache_cp->charset))) {

```

I attached the dmesg and backtrace for debugging purposes. Let me know if you need more information.

Best,

Chenglong

PID: 52596    TASK: ffff992c92edc300  CPU: 9    COMMAND: "mount.cifs"
 #0 [ffffb3dbc34fb948] machine_kexec at ffffffff94075f75
    /build/lakitu/tmp/portage/sys-kernel/lakitu-kernel-5_15-5.15.146-r181/work/lakitu-kernel-5_15-5.15.146/arch/x86/kernel/machine_kexec_64
.c: 358
 #1 [ffffb3dbc34fb9c8] crash_kexec at ffffffff94164be3
    /build/lakitu/tmp/portage/sys-kernel/lakitu-kernel-5_15-5.15.146-r181/work/lakitu-kernel-5_15-5.15.146/include/linux/atomic/atomic-arch
-fallback.h: 173
 #2 [ffffb3dbc34fba98] oops_end at ffffffff94041b46
    /build/lakitu/tmp/portage/sys-kernel/lakitu-kernel-5_15-5.15.146-r181/work/lakitu-kernel-5_15-5.15.146/arch/x86/kernel/dumpstack.c: 364
 #3 [ffffb3dbc34fbac0] page_fault_oops at ffffffff94088ca7
    /build/lakitu/tmp/portage/sys-kernel/lakitu-kernel-5_15-5.15.146-r181/work/lakitu-kernel-5_15-5.15.146/arch/x86/mm/fault.c: 708
 #4 [ffffb3dbc34fbb50] exc_page_fault at ffffffff94b61e06
    /build/lakitu/tmp/portage/sys-kernel/lakitu-kernel-5_15-5.15.146-r181/work/lakitu-kernel-5_15-5.15.146/arch/x86/mm/fault.c: 1483
 #5 [ffffb3dbc34fbb80] asm_exc_page_fault at ffffffff94c00ba2
    /build/lakitu/tmp/portage/sys-kernel/lakitu-kernel-5_15-5.15.146-r181/work/lakitu-kernel-5_15-5.15.146/arch/x86/include/asm/idtentry.h:
 568
    [exception RIP: dfs_cache_canonical_path+98]
    RIP: ffffffffc069dde2  RSP: ffffb3dbc34fbc38  RFLAGS: 00010246
    RAX: ffffffff00000000  RBX: ffff992ddd978941  RCX: 0000000000000001
    RDX: 0000000000000001  RSI: ffffffffc0727100  RDI: ffffffffc0726000
    RBP: ffffb3dbc34fbc70   R8: ffff992ddd978941   R9: 0000000000000000
    R10: ffffb3dbc34fbce8  R11: ffffffffc0682cb0  R12: ffffffffc0727100
    R13: 0000000000000032  R14: ffffffffffffffea  R15: 0000000000000001
    ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018
    /build/lakitu/tmp/portage/sys-kernel/lakitu-kernel-5_15-5.15.146-r181/work/lakitu-kernel-5_15-5.15.146/fs/cifs/dfs_cache.c: 197
 #6 [ffffb3dbc34fbc78] dfs_cache_find at ffffffffc069e32b [cifs]
    /build/lakitu/tmp/portage/sys-kernel/lakitu-kernel-5_15-5.15.146-r181/work/lakitu-kernel-5_15-5.15.146/fs/cifs/dfs_cache.c: 956
 #7 [ffffb3dbc34fbcb8] cifs_mount at ffffffffc0653afc [cifs]
    /build/lakitu/tmp/portage/sys-kernel/lakitu-kernel-5_15-5.15.146-r181/work/lakitu-kernel-5_15-5.15.146/fs/cifs/connect.c: 3344
 #8 [ffffb3dbc34fbda8] cifs_smb3_do_mount at ffffffffc06433ff [cifs]
    /build/lakitu/tmp/portage/sys-kernel/lakitu-kernel-5_15-5.15.146-r181/work/lakitu-kernel-5_15-5.15.146/fs/cifs/cifsfs.c: 894
 #9 [ffffb3dbc34fbe00] smb3_get_tree at ffffffffc069b809 [cifs]
    /build/lakitu/tmp/portage/sys-kernel/lakitu-kernel-5_15-5.15.146-r181/work/lakitu-kernel-5_15-5.15.146/include/linux/err.h: 36
#10 [ffffb3dbc34fbe28] vfs_get_tree at ffffffff94323beb
    /build/lakitu/tmp/portage/sys-kernel/lakitu-kernel-5_15-5.15.146-r181/work/lakitu-kernel-5_15-5.15.146/fs/super.c: 1518
#11 [ffffb3dbc34fbe58] do_new_mount at ffffffff9434de37
    /build/lakitu/tmp/portage/sys-kernel/lakitu-kernel-5_15-5.15.146-r181/work/lakitu-kernel-5_15-5.15.146/fs/namespace.c: 2994
#12 [ffffb3dbc34fbec0] __se_sys_mount at ffffffff9434e9a9
    /build/lakitu/tmp/portage/sys-kernel/lakitu-kernel-5_15-5.15.146-r181/work/lakitu-kernel-5_15-5.15.146/fs/namespace.c: 3337
#13 [ffffb3dbc34fbf18] do_syscall_64 at ffffffff94b5e6d1
    /build/lakitu/tmp/portage/sys-kernel/lakitu-kernel-5_15-5.15.146-r181/work/lakitu-kernel-5_15-5.15.146/arch/x86/entry/common.c: 50
#14 [ffffb3dbc34fbf50] entry_SYSCALL_64_after_hwframe at ffffffff94c000da
    /build/lakitu/tmp/portage/sys-kernel/lakitu-kernel-5_15-5.15.146-r181/work/lakitu-kernel-5_15-5.15.146/arch/x86/entry/entry_64.S: 118
    RIP: 00007f570da5db7a  RSP: 00007ffe92d16c58  RFLAGS: 00000202
    RAX: ffffffffffffffda  RBX: 00005574c76cceb0  RCX: 00007f570da5db7a
    RDX: 00005574c5ed345b  RSI: 00005574c5ed34fa  RDI: 00007ffe92d178a2
    RBP: 00005574c5ed3109   R8: 00005574c76cceb0   R9: 00007ffe92d15ff0
    R10: 0000000000000000  R11: 0000000000000202  R12: 00007ffe92d178a2
    R13: 00005574c76cdf40  R14: 000000000000000a  R15: 00007f570d94e000
    ORIG_RAX: 00000000000000a5  CS: 0033  SS: 002b