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

[Bradley Morgan]

On 2 September 2026 13:21:36 BST, Mimi Zohar <zohar@xxxxxxxxxxxxx> wrote:
>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@xxxxxxxxxxxxxxx
>> Reported-by: syzbot+5ebeb3089ea6439c37be@xxxxxxxxxxxxxxxxxxxxxxxxx
>> Link:
>https://lore.kernel.org/all/6a8f89e5.1d9ded08.62e62.00bf.GAE@xxxxxxxxxx/
>> Signed-off-by: Bradley Morgan <brads@xxxxxxxxxxxxxx>
>
>Thanks, Bradley.  The patch is now queued in next-integrity.

Cheers, +CC Paul, the syzbot issue should now be fixed

>
>Mimi

--- Thanks!
https://lore.kernel.org/all/EE579805-42F2-4C58-B752-F28779EEB717@xxxxxxxxx/