[Cluster-devel] [PATCH GFS2] Fix kernel NULL pointer dereference by dlm_astd

[Cluster-devel] [PATCH GFS2] Fix kernel NULL pointer dereference by dlm_astd

[Bob Peterson]

Hi,

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.

This problem was discovered while testing bugzilla bug #595397.

Regards,

Bob Peterson
Red Hat GFS

Signed-off-by: Bob Peterson <rpeterso@redhat.com> 
--
 fs/gfs2/inode.c |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/gfs2/inode.c b/fs/gfs2/inode.c
index b5612cb..43e06ff 100644
--- a/fs/gfs2/inode.c
+++ b/fs/gfs2/inode.c
@@ -197,8 +197,6 @@ struct inode *gfs2_inode_lookup(struct super_block *sb,
 			goto fail_iopen;
 		ip->i_iopen_gh.gh_gl->gl_object = ip;
 
-		gfs2_glock_put(io_gl);
-
 		if ((type == DT_UNKNOWN) && (no_formal_ino == 0))
 			goto gfs2_nfsbypass;
 
@@ -224,6 +222,8 @@ struct inode *gfs2_inode_lookup(struct super_block *sb,
 	}
 
 gfs2_nfsbypass:
+	gfs2_glock_put(io_gl);
+
 	return inode;
 fail_glock:
 	gfs2_glock_dq(&ip->i_iopen_gh);
@@ -292,7 +292,6 @@ void gfs2_process_unlinked_inode(struct super_block *sb, u64 no_addr)
 		goto fail_iopen;
 
 	ip->i_iopen_gh.gh_gl->gl_object = ip;
-	gfs2_glock_put(io_gl);
 
 	inode->i_mode = DT2IF(DT_UNKNOWN);
 
@@ -310,6 +309,7 @@ void gfs2_process_unlinked_inode(struct super_block *sb, u64 no_addr)
 
 	/* Inode is now uptodate */
 	gfs2_glock_dq_uninit(&gh);
+	gfs2_glock_put(io_gl);
 	gfs2_set_iop(inode);
 
 	/* The iput will cause it to be deleted. */

[Cluster-devel] [PATCH GFS2] Fix kernel NULL pointer dereference by dlm_astd

[Steven Whitehouse]

Hi,

Now in the -nmw GFS2 tree. Thanks,

Steve.

On Tue, 2010-06-15 at 12:07 -0400, Bob Peterson wrote:
> Hi,
> 
> 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.
> 
> This problem was discovered while testing bugzilla bug #595397.
> 
> Regards,
> 
> Bob Peterson
> Red Hat GFS
> 
> Signed-off-by: Bob Peterson <rpeterso@redhat.com> 
> --
>  fs/gfs2/inode.c |    6 +++---
>  1 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/gfs2/inode.c b/fs/gfs2/inode.c
> index b5612cb..43e06ff 100644
> --- a/fs/gfs2/inode.c
> +++ b/fs/gfs2/inode.c
> @@ -197,8 +197,6 @@ struct inode *gfs2_inode_lookup(struct super_block *sb,
>  			goto fail_iopen;
>  		ip->i_iopen_gh.gh_gl->gl_object = ip;
>  
> -		gfs2_glock_put(io_gl);
> -
>  		if ((type == DT_UNKNOWN) && (no_formal_ino == 0))
>  			goto gfs2_nfsbypass;
>  
> @@ -224,6 +222,8 @@ struct inode *gfs2_inode_lookup(struct super_block *sb,
>  	}
>  
>  gfs2_nfsbypass:
> +	gfs2_glock_put(io_gl);
> +
>  	return inode;
>  fail_glock:
>  	gfs2_glock_dq(&ip->i_iopen_gh);
> @@ -292,7 +292,6 @@ void gfs2_process_unlinked_inode(struct super_block *sb, u64 no_addr)
>  		goto fail_iopen;
>  
>  	ip->i_iopen_gh.gh_gl->gl_object = ip;
> -	gfs2_glock_put(io_gl);
>  
>  	inode->i_mode = DT2IF(DT_UNKNOWN);
>  
> @@ -310,6 +309,7 @@ void gfs2_process_unlinked_inode(struct super_block *sb, u64 no_addr)
>  
>  	/* Inode is now uptodate */
>  	gfs2_glock_dq_uninit(&gh);
> +	gfs2_glock_put(io_gl);
>  	gfs2_set_iop(inode);
>  
>  	/* The iput will cause it to be deleted. */

[Cluster-devel] [PATCH GFS2] Fix kernel NULL pointer dereference by dlm_astd

[Bob Peterson]

----- "Steven Whitehouse" <swhiteho@redhat.com> wrote:
| Hi,
| 
| Now in the -nmw GFS2 tree. Thanks,
| 
| Steve.
| 
| On Tue, 2010-06-15 at 12:07 -0400, Bob Peterson wrote:
| > Hi,
| > 
| > 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.
| > 
| > This problem was discovered while testing bugzilla bug #595397.
| > 
| > Regards,
| > 
| > Bob Peterson
| > Red Hat GFS

Hi,

Actually, it's not yet in the -nmw git tree.  I think Steve W.
forgot to push it before he left on holiday.  At any rate, that's a
good thing because my testing has uncovered a possible problem
with this patch.  I'm planning to rework it and re-post when
I get a stable version.

Regards,

Bob Peterson
Red Hat File Systems

[Cluster-devel] [PATCH GFS2] Fix kernel NULL pointer dereference by dlm_astd

[Bob Peterson]

Hi,

This patch replaces the one I previously posted here.

Regards,

Bob Peterson
Red Hat File Systems
--
commit 77ac19b0f0061396d0dc15f705ac4e0a574bd614
Author: Bob Peterson <rpeterso@redhat.com>
Date:   Thu Jun 17 15:38:32 2010 -0500

    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.
    
    rhbz#604244

diff --git a/fs/gfs2/inode.c b/fs/gfs2/inode.c
index 4a1f236..21f901f 100644
--- a/fs/gfs2/inode.c
+++ b/fs/gfs2/inode.c
@@ -171,7 +171,7 @@ 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);
@@ -200,6 +200,7 @@ 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;
@@ -230,7 +231,8 @@ 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;
@@ -258,7 +260,7 @@ 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;
@@ -295,6 +297,7 @@ 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);
 
@@ -321,7 +324,8 @@ 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);

[Cluster-devel] [PATCH GFS2] Fix kernel NULL pointer dereference by dlm_astd

[Steven Whitehouse]

Hi,

This really is in the -nmw tree this time. Sorry for the earlier
confusion. Thanks,

Steve.

On Thu, 2010-06-17 at 16:45 -0400, Bob Peterson wrote:
> Hi,
> 
> This patch replaces the one I previously posted here.
> 
> Regards,
> 
> Bob Peterson
> Red Hat File Systems
> --
> commit 77ac19b0f0061396d0dc15f705ac4e0a574bd614
> Author: Bob Peterson <rpeterso@redhat.com>
> Date:   Thu Jun 17 15:38:32 2010 -0500
> 
>     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.
>     
>     rhbz#604244
> 
> diff --git a/fs/gfs2/inode.c b/fs/gfs2/inode.c
> index 4a1f236..21f901f 100644
> --- a/fs/gfs2/inode.c
> +++ b/fs/gfs2/inode.c
> @@ -171,7 +171,7 @@ 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);
> @@ -200,6 +200,7 @@ 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;
> @@ -230,7 +231,8 @@ 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;
> @@ -258,7 +260,7 @@ 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;
> @@ -295,6 +297,7 @@ 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);
>  
> @@ -321,7 +324,8 @@ 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);
>