FAILED: patch "[PATCH] cifs: check pointer before freeing" failed to apply to 5.4-stable tree

PATCH [email protected] 2 participants 2 messages Jan 17, 2021 – Jan 18, 2021 Stable branch

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2021-01-17 14:17 UTC #0 lore raw

The patch below does not apply to the 5.4-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 77b6ec01c29aade01701aa30bf1469acc7f2be76 Mon Sep 17 00:00:00 2001
From: Tom Rix <[email protected]>
Date: Tue, 5 Jan 2021 12:21:26 -0800
Subject: [PATCH] cifs: check pointer before freeing

clang static analysis reports this problem

dfs_cache.c:591:2: warning: Argument to kfree() is a constant address
(18446744073709551614), which is not memory allocated by malloc()

        kfree(vi);
        ^~~~~~~~~

In dfs_cache_del_vol() the volume info pointer 'vi' being freed is the return of a call to find_vol(). The large constant address is find_vol() returning an error.

Add an error check to dfs_cache_del_vol() similar to the one done in dfs_cache_update_vol().

Fixes 54be1f6c1c37 ("cifs: Add DFS cache routines")

Signed-off-by Tom Rix <[email protected]>

Reviewed-by Nathan Chancellor <[email protected]>

CC <[email protected]> # v5.0+

Signed-off-by Steve French <[email protected]>

fs/cifs/dfs_cache.c +2 -1

index 6ad6ba5f6ebe..0fdb0de7ff86 100644
@@ -1260,7 +1260,8 @@ void dfs_cache_del_vol(const char *fullpath)
 	vi = find_vol(fullpath);
 	spin_unlock(&vol_list_lock);
 
-	kref_put(&vi->refcnt, vol_release);
+	if (!IS_ERR(vi))
+		kref_put(&vi->refcnt, vol_release);
 }
 
 /**

Tom Rix

2021-01-18 21:45 UTC #1 lore raw

I made a mistake on the fixes line, it should have been

Fixes 06d57378bcc9 ("cifs: Fix potential deadlock when updating vol in cifs_reconnect()")

-       if (!IS_ERR(vi))
-               free_vol(vi);
-       mutex_unlock(&vol_lock);
+       spin_unlock(&vol_list_lock);
+
+       kref_put(&vi->refcnt, vol_release);

This change is not needed for 5.4 unless the deadlock change is also needed.

Tom

Quoted 51 lines · On 1/17/21 6:16 AM, [email protected] wrote:

The patch below does not apply to the 5.4-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 77b6ec01c29aade01701aa30bf1469acc7f2be76 Mon Sep 17 00:00:00 2001
From: Tom Rix <[email protected]>
Date: Tue, 5 Jan 2021 12:21:26 -0800
Subject: [PATCH] cifs: check pointer before freeing
clang static analysis reports this problem
dfs_cache.c:591:2: warning: Argument to kfree() is a constant address
(18446744073709551614), which is not memory allocated by malloc()
        kfree(vi);
        ^~~~~~~~~
In dfs_cache_del_vol() the volume info pointer 'vi' being freed is the return of a call to find_vol(). The large constant address is find_vol() returning an error.
Add an error check to dfs_cache_del_vol() similar to the one done in dfs_cache_update_vol().
Fixes 54be1f6c1c37 ("cifs: Add DFS cache routines")
Signed-off-by Tom Rix <[email protected]>
Reviewed-by Nathan Chancellor <[email protected]>
CC <[email protected]> # v5.0+
Signed-off-by Steve French <[email protected]>
fs/cifs/dfs_cache.c +2 -1
index 6ad6ba5f6ebe..0fdb0de7ff86 100644
@@ -1260,7 +1260,8 @@ void dfs_cache_del_vol(const char *fullpath)
 	vi = find_vol(fullpath);
 	spin_unlock(&vol_list_lock);
 
-	kref_put(&vi->refcnt, vol_release);
+	if (!IS_ERR(vi))
+		kref_put(&vi->refcnt, vol_release);
 }
 
 /**