From 509e708a8929c5b75a16c985c03db5329e09cad4 Mon Sep 17 00:00:00 2001
From: Dave Chinner <dchinner@redhat.com>
Date: Mon, 20 May 2013 09:51:10 +1000
Subject: [PATCH] xfs: Don't reference the EFI after it is freed
Checking the EFI for whether it is being released from recovery
after we've already released the known active reference is a mistake
worthy of a brown paper bag. Fix the (now) obvious use after free
that it can cause.
Reported-by: Dave Jones <davej@redhat.com>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
(cherry picked from commit 52c24ad39ff02d7bd73c92eb0c926fb44984a41d)
---
fs/xfs/xfs_extfree_item.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/fs/xfs/xfs_extfree_item.c b/fs/xfs/xfs_extfree_item.c
index c0f375087efc32..452920a3f03fb2 100644
--- a/fs/xfs/xfs_extfree_item.c
+++ b/fs/xfs/xfs_extfree_item.c
@@ -305,11 +305,12 @@ xfs_efi_release(xfs_efi_log_item_t *efip,
{
ASSERT(atomic_read(&efip->efi_next_extent) >= nextents);
if (atomic_sub_and_test(nextents, &efip->efi_next_extent)) {
- __xfs_efi_release(efip);
-
/* recovery needs us to drop the EFI reference, too */
if (test_bit(XFS_EFI_RECOVERED, &efip->efi_flags))
__xfs_efi_release(efip);
+
+ __xfs_efi_release(efip);
+ /* efip may now have been freed, do not reference it again. */
}
}
--
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