gfs2: Check for the end of metadata in punch_hole (bb491ce6) · Commits · 戴 / test

When punching a hole or truncating an inode down to a given size, also check if the truncate point / start of the hole is within the range we have metadata for. Otherwise, we can end up freeing blocks that shouldn't be freed, corrupting the inode, or crashing the machine when trying to punch a hole into the void. When growing an inode via truncate, we set the new size but we don't allocate additional levels of indirect blocks and grow the inode height. When shrinking that inode again, the new size may still point beyond the end of the inode's metadata. Fixes xfstest generic/476. Debugged-by:

Bob Peterson <rpeterso@redhat.com> Signed-off-by:

Andreas Gruenbacher <agruenba@redhat.com> Signed-off-by:

Bob Peterson <rpeterso@redhat.com>

fs/gfs2/bmap.c

+9 −1

Original line number	Diff line number	Diff line
		@@ -1351,6 +1351,7 @@ static inline bool walk_done(struct gfs2_sbd *sdp,
		static int punch_hole(struct gfs2_inode *ip, u64 offset, u64 length)
		{
		struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
		u64 maxsize = sdp->sd_heightsize[ip->i_height];
		struct metapath mp = {};
		struct buffer_head dibh, bh;
		struct gfs2_holder rd_gh;
		@@ -1366,6 +1367,14 @@ static int punch_hole(struct gfs2_inode *ip, u64 offset, u64 length)
		u64 prev_bnr = 0;
		__be64 start, end;

		if (offset >= maxsize) {
		/*
		* The starting point lies beyond the allocated meta-data;
		* there are no blocks do deallocate.
		*/
		return 0;
		}

		/*
		* The start position of the hole is defined by lblock, start_list, and
		* start_aligned. The end position of the hole is defined by lend,
		@@ -1379,7 +1388,6 @@ static int punch_hole(struct gfs2_inode *ip, u64 offset, u64 length)
		*/

		if (length) {
		u64 maxsize = sdp->sd_heightsize[ip->i_height];
		u64 end_offset = offset + length;
		u64 lend;

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