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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: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
This commit is contained in:
Bob Peterson 2010-06-17 16:45:37 -04:00 committed by Steven Whitehouse
parent b7dc2df572
commit b1becbdee7
1 changed files with 8 additions and 4 deletions
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12
fs/gfs2/inode.c
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@ -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;
@ -228,7 +229,8 @@ gfs2_nfsbypass:
fail_glock:
gfs2_glock_dq(&ip->i_iopen_gh);
fail_iopen:
gfs2_glock_put(io_gl);
if (io_gl)
gfs2_glock_put(io_gl);
fail_put:
if (inode->i_state & I_NEW)
ip->i_gl->gl_object = NULL;
@ -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);
@ -319,7 +322,8 @@ void gfs2_process_unlinked_inode(struct super_block *sb, u64 no_addr)
fail_glock:
gfs2_glock_dq(&ip->i_iopen_gh);
fail_iopen:
gfs2_glock_put(io_gl);
if (io_gl)
gfs2_glock_put(io_gl);
fail_put:
ip->i_gl->gl_object = NULL;
gfs2_glock_put(ip->i_gl);