smb: client: fix missing lower-bound check on DFS referral string offsets

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parse_dfs_referrals() checks that DfsPathOffset and NetworkAddressOffset
do not exceed the buffer end, but fails to check that they don't point
inside the referral header itself.

If a server provides an offset smaller than
sizeof(struct dfs_referral_level_3), the derived string pointer overlaps
with the struct fields, causing cifs_strndup_from_utf16() to interpret
header data as UTF-16 strings.

Fix this by enforcing that string offsets are at least sizeof(*ref).

Fixes: 4ecce920e1 ("CIFS: move DFS response parsing out of SMB1 code")
Cc: stable@vger.kernel.org
Signed-off-by: Frank Sorenson <sorenson@redhat.com>
Reviewed-by: David Howells <dhowells@redhat.com>
Signed-off-by: Paulo Alcantara <pc@manguebit.org>

...

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Frank Sorenson 2026-09-16 16:33:55 -05:00 • committed by Paulo Alcantara

parent f73726b83e

commit e83330c55e

1 changed files with 10 additions and 2 deletions

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fs/smb/client/misc.c

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