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authorTheodore Ts'o <tytso@mit.edu>2012-11-29 21:21:22 -0500
committerTheodore Ts'o <tytso@mit.edu>2012-11-29 21:21:22 -0500
commitaeb1e5d69a5be592e86a926be73efb38c55af404 (patch)
treeaddd38abf4d74fc6fd54829cff1c3fb9fb832c31
parent69c499d152a7fe2c4443e5ddd91568ad5a79145a (diff)
ext4: fix possible use after free with metadata csum
Commit fa77dcfafeaa introduces block bitmap checksum calculation into ext4_new_inode() in the case that block group was uninitialized. However we brelse() the bitmap buffer before we attempt to checksum it so we have no guarantee that the buffer is still there. Fix this by releasing the buffer after the possible checksum computation. Signed-off-by: Lukas Czerner <lczerner@redhat.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Acked-by: Darrick J. Wong <darrick.wong@oracle.com> Cc: stable@vger.kernel.org
-rw-r--r--fs/ext4/ialloc.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
index 3a100e7a62a..c7efa88d714 100644
--- a/fs/ext4/ialloc.c
+++ b/fs/ext4/ialloc.c
@@ -762,7 +762,6 @@ got:
BUFFER_TRACE(block_bitmap_bh, "dirty block bitmap");
err = ext4_handle_dirty_metadata(handle, NULL, block_bitmap_bh);
- brelse(block_bitmap_bh);
/* recheck and clear flag under lock if we still need to */
ext4_lock_group(sb, group);
@@ -775,6 +774,7 @@ got:
ext4_group_desc_csum_set(sb, group, gdp);
}
ext4_unlock_group(sb, group);
+ brelse(block_bitmap_bh);
if (err)
goto fail;