This is a note to let you know that I've just added the patch titled
jffs2: fix use after free in jffs2_sum_write_data()
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
jffs2-fix-use-after-free-in-jffs2_sum_write_data.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit cf9ce47084e44214fcb4bbbb3802344ca700f416
Author: Tom Rix <trix@xxxxxxxxxx>
Date: Wed Dec 30 06:56:04 2020 -0800
jffs2: fix use after free in jffs2_sum_write_data()
[ Upstream commit 19646447ad3a680d2ab08c097585b7d96a66126b ]
clang static analysis reports this problem
fs/jffs2/summary.c:794:31: warning: Use of memory after it is freed
c->summary->sum_list_head = temp->u.next;
^~~~~~~~~~~~
In jffs2_sum_write_data(), in a loop summary data is handles a node at
a time. When it has written out the node it is removed the summary list,
and the node is deleted. In the corner case when a
JFFS2_FEATURE_RWCOMPAT_COPY is seen, a call is made to
jffs2_sum_disable_collecting(). jffs2_sum_disable_collecting() deletes
the whole list which conflicts with the loop's deleting the list by parts.
To preserve the old behavior of stopping the write midway, bail out of
the loop after disabling summary collection.
Fixes: 6171586a7ae5 ("[JFFS2] Correct handling of JFFS2_FEATURE_RWCOMPAT_COPY nodes.")
Signed-off-by: Tom Rix <trix@xxxxxxxxxx>
Reviewed-by: Nathan Chancellor <natechancellor@xxxxxxxxx>
Signed-off-by: Richard Weinberger <richard@xxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/jffs2/summary.c b/fs/jffs2/summary.c
index be7c8a6a57480..4fe64519870f1 100644
--- a/fs/jffs2/summary.c
+++ b/fs/jffs2/summary.c
@@ -783,6 +783,8 @@ static int jffs2_sum_write_data(struct jffs2_sb_info *c, struct jffs2_eraseblock
dbg_summary("Writing unknown RWCOMPAT_COPY node type %x\n",
je16_to_cpu(temp->u.nodetype));
jffs2_sum_disable_collecting(c->summary);
+ /* The above call removes the list, nothing more to do */
+ goto bail_rwcompat;
} else {
BUG(); /* unknown node in summary information */
}
@@ -794,6 +796,7 @@ static int jffs2_sum_write_data(struct jffs2_sb_info *c, struct jffs2_eraseblock
c->summary->sum_num--;
}
+ bail_rwcompat:
jffs2_sum_reset_collected(c->summary);
