diff mbox

[02/19] e2fsck: never free critical metadata blocks in the block found map

Message ID 20140801181153.12496.71297.stgit@birch.djwong.org
State Accepted, archived
Headers show

Commit Message

Darrick Wong Aug. 1, 2014, 6:11 p.m. UTC 
From: Darrick J. Wong <darrick.wong@oracle.com>

Don't allow critical metadata blocks to be marked free in the block
found map.  This can theoretically happen on an FS where a first
inode's ETB/indirect map block is in the inode table, the first inode
is itself unclonable (and thus gets deleted) and there are enough
crosslinked files before and after the first inode to use up all the
free blocks during pass 1b.

(I do actually have a test FS image but it's 256M and it proved very
difficult to craft a bite-sized test case that actually hit this bug.)

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 e2fsck/pass1.c |    7 +++++++
 1 file changed, 7 insertions(+)


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Comments

Theodore Ts'o Aug. 3, 2014, 2:22 a.m. UTC | #1 
On Fri, Aug 01, 2014 at 11:11:53AM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@oracle.com>
> 
> Don't allow critical metadata blocks to be marked free in the block
> found map.  This can theoretically happen on an FS where a first
> inode's ETB/indirect map block is in the inode table, the first inode
> is itself unclonable (and thus gets deleted) and there are enough
> crosslinked files before and after the first inode to use up all the
> free blocks during pass 1b.
> 
> (I do actually have a test FS image but it's 256M and it proved very
> difficult to craft a bite-sized test case that actually hit this bug.)
> 
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

Applied, thanks.

						- Ted
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diff mbox

Patch

diff --git a/e2fsck/pass1.c b/e2fsck/pass1.c
index 26fe60c..e7a6acd 100644
--- a/e2fsck/pass1.c
+++ b/e2fsck/pass1.c
@@ -3356,6 +3356,13 @@  static void e2fsck_block_alloc_stats(ext2_filsys fs, blk64_t blk, int inuse)
 {
 	e2fsck_t ctx = (e2fsck_t) fs->priv_data;
 
+	/* Never free a critical metadata block */
+	if (ctx->block_found_map &&
+	    ctx->block_metadata_map &&
+	    inuse < 0 &&
+	    ext2fs_test_block_bitmap2(ctx->block_metadata_map, blk))
+		return;
+
 	if (ctx->block_found_map) {
 		if (inuse > 0)
 			ext2fs_mark_block_bitmap2(ctx->block_found_map, blk);