From: Lachlan McIlroy Date: Wed, 17 Sep 2008 06:52:13 +0000 (+1000) Subject: [XFS] Fix use-after-free with buffers X-Git-Tag: Ubuntu-5.0.0-8.9~31266^2~1 X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=e1f5dbd7077eebec794452a516cb02f1669b036d;p=mirror_ubuntu-disco-kernel.git [XFS] Fix use-after-free with buffers We have a use-after-free issue where log completions access buffers via the buffer log item and the buffer has already been freed. Fix this by taking a reference on the buffer when attaching the buffer log item and release the hold when the buffer log item is detached and we no longer need the buffer. Also create a new function xfs_buf_item_free() to combine some common code. SGI-PV: 985757 SGI-Modid: xfs-linux-melb:xfs-kern:32025a Signed-off-by: Lachlan McIlroy Signed-off-by: Christoph Hellwig --- diff --git a/fs/xfs/xfs_buf_item.c b/fs/xfs/xfs_buf_item.c index 608c30c3f76b..002fc2617c8e 100644 --- a/fs/xfs/xfs_buf_item.c +++ b/fs/xfs/xfs_buf_item.c @@ -732,6 +732,7 @@ xfs_buf_item_init( bip->bli_item.li_ops = &xfs_buf_item_ops; bip->bli_item.li_mountp = mp; bip->bli_buf = bp; + xfs_buf_hold(bp); bip->bli_format.blf_type = XFS_LI_BUF; bip->bli_format.blf_blkno = (__int64_t)XFS_BUF_ADDR(bp); bip->bli_format.blf_len = (ushort)BTOBB(XFS_BUF_COUNT(bp)); @@ -867,6 +868,21 @@ xfs_buf_item_dirty( return (bip->bli_flags & XFS_BLI_DIRTY); } +STATIC void +xfs_buf_item_free( + xfs_buf_log_item_t *bip) +{ +#ifdef XFS_TRANS_DEBUG + kmem_free(bip->bli_orig); + kmem_free(bip->bli_logged); +#endif /* XFS_TRANS_DEBUG */ + +#ifdef XFS_BLI_TRACE + ktrace_free(bip->bli_trace); +#endif + kmem_zone_free(xfs_buf_item_zone, bip); +} + /* * This is called when the buf log item is no longer needed. It should * free the buf log item associated with the given buffer and clear @@ -887,18 +903,8 @@ xfs_buf_item_relse( (XFS_BUF_IODONE_FUNC(bp) != NULL)) { XFS_BUF_CLR_IODONE_FUNC(bp); } - -#ifdef XFS_TRANS_DEBUG - kmem_free(bip->bli_orig); - bip->bli_orig = NULL; - kmem_free(bip->bli_logged); - bip->bli_logged = NULL; -#endif /* XFS_TRANS_DEBUG */ - -#ifdef XFS_BLI_TRACE - ktrace_free(bip->bli_trace); -#endif - kmem_zone_free(xfs_buf_item_zone, bip); + xfs_buf_rele(bp); + xfs_buf_item_free(bip); } @@ -1120,6 +1126,7 @@ xfs_buf_iodone( ASSERT(bip->bli_buf == bp); + xfs_buf_rele(bp); mp = bip->bli_item.li_mountp; /* @@ -1136,18 +1143,7 @@ xfs_buf_iodone( * xfs_trans_delete_ail() drops the AIL lock. */ xfs_trans_delete_ail(mp, (xfs_log_item_t *)bip); - -#ifdef XFS_TRANS_DEBUG - kmem_free(bip->bli_orig); - bip->bli_orig = NULL; - kmem_free(bip->bli_logged); - bip->bli_logged = NULL; -#endif /* XFS_TRANS_DEBUG */ - -#ifdef XFS_BLI_TRACE - ktrace_free(bip->bli_trace); -#endif - kmem_zone_free(xfs_buf_item_zone, bip); + xfs_buf_item_free(bip); } #if defined(XFS_BLI_TRACE)