Re: [PATCH] cifs: fix leak in cifs_smb3_do_mount() ctx

[Paulo Alcantara <pc@cjr.nz>]

David Disseldorp <ddiss@suse.de> writes:

> cifs_smb3_do_mount() calls smb3_fs_context_dup() and then
> cifs_setup_volume_info(). The latter's subsequent smb3_parse_devname()
> call overwrites the cifs_sb->ctx->UNC string already dup'ed by
> smb3_fs_context_dup(), resulting in a leak. E.g.
>
> unreferenced object 0xffff888002980420 (size 32):
>   comm "mount", pid 160, jiffies 4294892541 (age 30.416s)
>   hex dump (first 32 bytes):
>     5c 5c 31 39 32 2e 31 36 38 2e 31 37 34 2e 31 30  \\192.168.174.10
>     34 5c 72 61 70 69 64 6f 2d 73 68 61 72 65 00 00  4\rapido-share..
>   backtrace:
>     [<00000000069e12f6>] kstrdup+0x28/0x50
>     [<00000000b61f4032>] smb3_fs_context_dup+0x127/0x1d0 [cifs]
>     [<00000000c6e3e3bf>] cifs_smb3_do_mount+0x77/0x660 [cifs]
>     [<0000000063467a6b>] smb3_get_tree+0xdf/0x220 [cifs]
>     [<00000000716f731e>] vfs_get_tree+0x1b/0x90
>     [<00000000491d3892>] path_mount+0x62a/0x910
>     [<0000000046b2e774>] do_mount+0x50/0x70
>     [<00000000ca7b64dd>] __x64_sys_mount+0x81/0xd0
>     [<00000000b5122496>] do_syscall_64+0x33/0x40
>     [<000000002dd397af>] entry_SYSCALL_64_after_hwframe+0x44/0xae
>
> This change is a bandaid until the cifs_setup_volume_info() TODO and
> error handling issues are resolved.
>
> Signed-off-by: David Disseldorp <ddiss@suse.de>
> ---
>  fs/cifs/cifsfs.c | 6 ++++++
>  1 file changed, 6 insertions(+)

Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz>