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

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

[Bradley Morgan]

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@vger.kernel.org
Reported-by: syzbot+5ebeb3089ea6439c37be@syzkaller.appspotmail.com
Link: https://lore.kernel.org/all/6a8f89e5.1d9ded08.62e62.00bf.GAE@google.com/
Signed-off-by: Bradley Morgan <brads@mainlining.org>
---
 security/integrity/ima/ima_appraise.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
index ced2e131b061..b280488e15fc 100644
--- a/security/integrity/ima/ima_appraise.c
+++ b/security/integrity/ima/ima_appraise.c
@@ -748,6 +748,8 @@ static int validate_hash_algo(struct dentry *dentry,
 		return -EACCES;
 
 	path = dentry_path(dentry, pathbuf, PATH_MAX);
+	if (IS_ERR(path))
+		path = NULL;
 
 	integrity_audit_msg(AUDIT_INTEGRITY_DATA, d_inode(dentry), path,
 			    "set_data", errmsg, -EACCES, 0);
-- 
2.47.3

Re: [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@vger.kernel.org
> Reported-by: syzbot+5ebeb3089ea6439c37be@syzkaller.appspotmail.com
> Link: https://lore.kernel.org/all/6a8f89e5.1d9ded08.62e62.00bf.GAE@google.com/
> Signed-off-by: Bradley Morgan <brads@mainlining.org>

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

Mimi

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@linux.ibm.com> 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@vger.kernel.org
>> Reported-by: syzbot+5ebeb3089ea6439c37be@syzkaller.appspotmail.com
>> Link:
>https://lore.kernel.org/all/6a8f89e5.1d9ded08.62e62.00bf.GAE@google.com/
>> Signed-off-by: Bradley Morgan <brads@mainlining.org>
>
>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@grrlz.net/