From 0c4da70c83d41a8461fdf50a3f7b292ecb04e378 Mon Sep 17 00:00:00 2001 From: Omar Sandoval Date: Tue, 26 Nov 2019 16:58:07 -0800 Subject: xfs: fix realtime file data space leak Realtime files in XFS allocate extents in rextsize units. However, the written/unwritten state of those extents is still tracked in blocksize units. Therefore, a realtime file can be split up into written and unwritten extents that are not necessarily aligned to the realtime extent size. __xfs_bunmapi() has some logic to handle these various corner cases. Consider how it handles the following case: 1. The last extent is unwritten. 2. The last extent is smaller than the realtime extent size. 3. startblock of the last extent is not aligned to the realtime extent size, but startblock + blockcount is. In this case, __xfs_bunmapi() calls xfs_bmap_add_extent_unwritten_real() to set the second-to-last extent to unwritten. This should merge the last and second-to-last extents, so __xfs_bunmapi() moves on to the second-to-last extent. However, if the size of the last and second-to-last extents combined is greater than MAXEXTLEN, xfs_bmap_add_extent_unwritten_real() does not merge the two extents. When that happens, __xfs_bunmapi() skips past the last extent without unmapping it, thus leaking the space. Fix it by only unwriting the minimum amount needed to align the last extent to the realtime extent size, which is guaranteed to merge with the last extent. Signed-off-by: Omar Sandoval Reviewed-by: Darrick J. Wong Signed-off-by: Darrick J. Wong --- fs/xfs/libxfs/xfs_bmap.c | 25 ++++++++++++++----------- 1 file changed, 14 insertions(+), 11 deletions(-) (limited to 'fs/xfs') diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c index 4acc6e37c31d..c943795b63f2 100644 --- a/fs/xfs/libxfs/xfs_bmap.c +++ b/fs/xfs/libxfs/xfs_bmap.c @@ -5480,16 +5480,17 @@ __xfs_bunmapi( } div_u64_rem(del.br_startblock, mp->m_sb.sb_rextsize, &mod); if (mod) { + xfs_extlen_t off = mp->m_sb.sb_rextsize - mod; + /* * Realtime extent is lined up at the end but not * at the front. We'll get rid of full extents if * we can. */ - mod = mp->m_sb.sb_rextsize - mod; - if (del.br_blockcount > mod) { - del.br_blockcount -= mod; - del.br_startoff += mod; - del.br_startblock += mod; + if (del.br_blockcount > off) { + del.br_blockcount -= off; + del.br_startoff += off; + del.br_startblock += off; } else if (del.br_startoff == start && (del.br_state == XFS_EXT_UNWRITTEN || tp->t_blk_res == 0)) { @@ -5507,6 +5508,7 @@ __xfs_bunmapi( continue; } else if (del.br_state == XFS_EXT_UNWRITTEN) { struct xfs_bmbt_irec prev; + xfs_fileoff_t unwrite_start; /* * This one is already unwritten. @@ -5520,12 +5522,13 @@ __xfs_bunmapi( ASSERT(!isnullstartblock(prev.br_startblock)); ASSERT(del.br_startblock == prev.br_startblock + prev.br_blockcount); - if (prev.br_startoff < start) { - mod = start - prev.br_startoff; - prev.br_blockcount -= mod; - prev.br_startblock += mod; - prev.br_startoff = start; - } + unwrite_start = max3(start, + del.br_startoff - mod, + prev.br_startoff); + mod = unwrite_start - prev.br_startoff; + prev.br_startoff = unwrite_start; + prev.br_startblock += mod; + prev.br_blockcount -= mod; prev.br_state = XFS_EXT_UNWRITTEN; error = xfs_bmap_add_extent_unwritten_real(tp, ip, whichfork, &icur, &cur, -- cgit v1.2.3 From 69ffe5960df16938bccfe1b65382af0b3de51265 Mon Sep 17 00:00:00 2001 From: Omar Sandoval Date: Tue, 26 Nov 2019 16:58:08 -0800 Subject: xfs: don't check for AG deadlock for realtime files in bunmapi Commit 5b094d6dac04 ("xfs: fix multi-AG deadlock in xfs_bunmapi") added a check in __xfs_bunmapi() to stop early if we would touch multiple AGs in the wrong order. However, this check isn't applicable for realtime files. In most cases, it just makes us do unnecessary commits. However, without the fix from the previous commit ("xfs: fix realtime file data space leak"), if the last and second-to-last extents also happen to have different "AG numbers", then the break actually causes __xfs_bunmapi() to return without making any progress, which sends xfs_itruncate_extents_flags() into an infinite loop. Fixes: 5b094d6dac04 ("xfs: fix multi-AG deadlock in xfs_bunmapi") Signed-off-by: Omar Sandoval Reviewed-by: Darrick J. Wong Signed-off-by: Darrick J. Wong --- fs/xfs/libxfs/xfs_bmap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'fs/xfs') diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c index c943795b63f2..a9ad1f991ba3 100644 --- a/fs/xfs/libxfs/xfs_bmap.c +++ b/fs/xfs/libxfs/xfs_bmap.c @@ -5404,7 +5404,7 @@ __xfs_bunmapi( * Make sure we don't touch multiple AGF headers out of order * in a single transaction, as that could cause AB-BA deadlocks. */ - if (!wasdel) { + if (!wasdel && !isrt) { agno = XFS_FSB_TO_AGNO(mp, del.br_startblock); if (prev_agno != NULLAGNUMBER && prev_agno > agno) break; -- cgit v1.2.3 From 798a9cada4694ca8d970259f216cec47e675bfd5 Mon Sep 17 00:00:00 2001 From: Brian Foster Date: Tue, 3 Dec 2019 07:53:15 -0800 Subject: xfs: fix mount failure crash on invalid iclog memory access syzbot (via KASAN) reports a use-after-free in the error path of xlog_alloc_log(). Specifically, the iclog freeing loop doesn't handle the case of a fully initialized ->l_iclog linked list. Instead, it assumes that the list is partially constructed and NULL terminated. This bug manifested because there was no possible error scenario after iclog list setup when the original code was added. Subsequent code and associated error conditions were added some time later, while the original error handling code was never updated. Fix up the error loop to terminate either on a NULL iclog or reaching the end of the list. Reported-by: syzbot+c732f8644185de340492@syzkaller.appspotmail.com Signed-off-by: Brian Foster Reviewed-by: Darrick J. Wong Signed-off-by: Darrick J. Wong --- fs/xfs/xfs_log.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'fs/xfs') diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c index 6a147c63a8a6..f6006d94a581 100644 --- a/fs/xfs/xfs_log.c +++ b/fs/xfs/xfs_log.c @@ -1542,6 +1542,8 @@ out_free_iclog: prev_iclog = iclog->ic_next; kmem_free(iclog->ic_data); kmem_free(iclog); + if (prev_iclog == log->l_iclog) + break; } out_free_log: kmem_free(log); -- cgit v1.2.3