From: Dave Chinner <dchinner@redhat.com>
Date: Sun, 19 May 2013 23:51:10 +0000 (+1000)
Subject: xfs: Don't reference the EFI after it is freed
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=509e708a8929c5b75a16c985c03db5329e09cad4;p=GitHub%2Fexynos8895%2Fandroid_kernel_samsung_universal8895.git

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)
---

diff --git a/fs/xfs/xfs_extfree_item.c b/fs/xfs/xfs_extfree_item.c
index c0f375087efc..452920a3f03f 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. */
 	}
 }