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Commit b1becbde authored by Bob Peterson's avatar Bob Peterson Committed by Steven Whitehouse
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GFS2: Fix kernel NULL pointer dereference by dlm_astd 



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: default avatarBob Peterson <rpeterso@redhat.com>
Signed-off-by: default avatarSteven Whitehouse <swhiteho@redhat.com>
parent b7dc2df5

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 @@ struct inode *gfs2_inode_lookup(struct super_block *sb, 
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;