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authorLinus Torvalds <torvalds@linux-foundation.org>2011-02-12 02:53:38 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2011-02-12 02:53:38 +0300
commit2dab597441667d6c04451a7dcf215241ad4c74f6 (patch)
treef56a6f7fcabf3a9b82a5e77ef9c96268224efbd1 /fs/open.c
parentd2478521afc20227658a10a8c5c2bf1a2aa615b3 (diff)
downloadlinux-2dab597441667d6c04451a7dcf215241ad4c74f6.tar.xz
Fix possible filp_cachep memory corruption
In commit 31e6b01f4183 ("fs: rcu-walk for path lookup") we started doing path lookup using RCU, which then falls back to a careful non-RCU lookup in case of problems (LOOKUP_REVAL). So do_filp_open() has this "re-do the lookup carefully" looping case. However, that means that we must not release the open-intent file data if we are going to loop around and use it once more! Fix this by moving the release of the open-intent data to the function that allocates it (do_filp_open() itself) rather than the helper functions that can get called multiple times (finish_open() and do_last()). This makes the logic for the lifetime of that field much more obvious, and avoids the possible double free. Reported-by: J. R. Okajima <hooanon05@yahoo.co.jp> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Cc: Nick Piggin <npiggin@kernel.dk> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/open.c')
-rw-r--r--fs/open.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/fs/open.c b/fs/open.c
index e52389e1f05b..5a2c6ebc22b5 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -790,6 +790,8 @@ struct file *nameidata_to_filp(struct nameidata *nd)
/* Pick up the filp from the open intent */
filp = nd->intent.open.file;
+ nd->intent.open.file = NULL;
+
/* Has the filesystem initialised the file for us? */
if (filp->f_path.dentry == NULL) {
path_get(&nd->path);