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Subject[PATCH][next][V3] btrfs: fix memory leak of path on error return path
Date
From: Colin Ian King <colin.king@canonical.com>

Currently if the allocation of roots or tmp_ulist fails the error handling
does not free up the allocation of path causing a memory leak. Fix this and
other similar leaks by moving the call of btrfs_free_path from label out
to label out_free_ulist.

Kudos to David Sterba for spotting the issue in my original fix and suggesting
the correct way to fix the leak and Anand Jain for spotting a double free
issue.

Addresses-Coverity: ("Resource leak")
Fixes: 5911c8fe05c5 ("btrfs: fiemap: preallocate ulists for btrfs_check_shared")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
V2: move the btrfs_free_path to the out_free_ulist label as suggested by
David Sterba as the correct fix.
V3: fix double free as identified Anand Jain
---

fs/btrfs/extent_io.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 1eb671c16ff1..9de119194f8e 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -4613,7 +4613,6 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
ret = btrfs_lookup_file_extent(NULL, root, path,
btrfs_ino(BTRFS_I(inode)), -1, 0);
if (ret < 0) {
- btrfs_free_path(path);
goto out_free_ulist;
} else {
WARN_ON(!ret);
@@ -4766,11 +4765,11 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
ret = emit_last_fiemap_cache(fieinfo, &cache);
free_extent_map(em);
out:
- btrfs_free_path(path);
unlock_extent_cached(&BTRFS_I(inode)->io_tree, start, start + len - 1,
&cached_state);

out_free_ulist:
+ btrfs_free_path(path);
ulist_free(roots);
ulist_free(tmp_ulist);
return ret;
--
2.20.1
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