GFS2: Fix kernel NULL pointer dereference by dlm_astd (b1becbde) · Commits · 戴 / test

This patch fixes a problem in an error path when looking up dinodes. There are two sister-functions, gfs2_inode_lookup and gfs2_process_unlinked_inode. Both functions acquire and hold the i_iopen glock for the dinode being looked up. The last thing they try to do is hold the i_gl glock for the dinode. If that glock fails for some reason, the error path was incorrectly calling gfs2_glock_put for the i_iopen glock twice. This resulted in the glock being prematurely freed. The "minimum hold time" usually kept the glock in memory, but the lock interface to dlm (aka lock_dlm) freed its memory for the glock. In some circumstances, it would cause dlm's dlm_astd daemon to try to call the bast function for the freed lock_dlm memory, which resulted in a NULL pointer dereference. Signed-off-by:

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

Steven Whitehouse <swhiteho@redhat.com>

fs/gfs2/inode.c

+8 −4

Original line number	Diff line number	Diff line
		@@ -169,7 +169,7 @@ struct inode gfs2_inode_lookup(struct super_block sb,
		{
		struct inode *inode;
		struct gfs2_inode *ip;
		struct gfs2_glock *io_gl;
		struct gfs2_glock *io_gl = NULL;
		int error;

		inode = gfs2_iget(sb, no_addr);
		@@ -198,6 +198,7 @@ struct inode gfs2_inode_lookup(struct super_block sb,
		ip->i_iopen_gh.gh_gl->gl_object = ip;

		gfs2_glock_put(io_gl);
		io_gl = NULL;

		if ((type == DT_UNKNOWN) && (no_formal_ino == 0))
		goto gfs2_nfsbypass;
		@@ -228,6 +229,7 @@ gfs2_nfsbypass:
		fail_glock:
		gfs2_glock_dq(&ip->i_iopen_gh);
		fail_iopen:
		if (io_gl)
		gfs2_glock_put(io_gl);
		fail_put:
		if (inode->i_state & I_NEW)
		@@ -256,7 +258,7 @@ void gfs2_process_unlinked_inode(struct super_block *sb, u64 no_addr)
		{
		struct gfs2_sbd *sdp;
		struct gfs2_inode *ip;
		struct gfs2_glock *io_gl;
		struct gfs2_glock *io_gl = NULL;
		int error;
		struct gfs2_holder gh;
		struct inode *inode;
		@@ -293,6 +295,7 @@ void gfs2_process_unlinked_inode(struct super_block *sb, u64 no_addr)

		ip->i_iopen_gh.gh_gl->gl_object = ip;
		gfs2_glock_put(io_gl);
		io_gl = NULL;

		inode->i_mode = DT2IF(DT_UNKNOWN);

		@@ -319,6 +322,7 @@ void gfs2_process_unlinked_inode(struct super_block *sb, u64 no_addr)
		fail_glock:
		gfs2_glock_dq(&ip->i_iopen_gh);
		fail_iopen:
		if (io_gl)
		gfs2_glock_put(io_gl);
		fail_put:
		ip->i_gl->gl_object = NULL;

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