[PATCH] ima: Check for ERR_PTR from dentry_path() in validate_hash_algo()

[Mimi Zohar]

On Thu, 2026-08-27 at 17:43 +0000, Bradley Morgan wrote:
> dentry_path() returns ERR_PTR(-ENAMETOOLONG) when the path exceeds the
> buffer. validate_hash_algo() passes the result straight to
> integrity_audit_msg() without checking. ERR_PTR is not NULL, so
> integrity_audit_message() sees a valid pointer and calls strlen() on
> it, which faults:
> 
>     BUG: unable to handle page fault for address: ffffffffffffffdc
>     RIP: 0010:strlen+0x30/0xa0
>     Call Trace:
>      audit_log_untrustedstring+0x19/0x30
>      integrity_audit_message+0x366/0x4f0
>      ima_inode_setxattr+0x512/0x5f0
> 
> Check for IS_ERR() and use NULL instead, which makes the audit message
> skip the name= field instead of crashing.
> 
> Fixes: 4f2946aa0c45 ("IMA: introduce a new policy option func=SETXATTR_CHECK")
> Cc: stable at vger.kernel.org
> Reported-by: syzbot+5ebeb3089ea6439c37be at syzkaller.appspotmail.com
> Link: https://lore.kernel.org/all/6a8f89e5.1d9ded08.62e62.00bf.GAE@google.com/
> Signed-off-by: Bradley Morgan <brads at mainlining.org>

Thanks, Bradley.  The patch is now queued in next-integrity.

Mimi