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Go Back   Linux Archive > Redhat > Cluster Development

 
 
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Old 06-25-2010, 09:52 AM
Steven Whitehouse
 
Default Fix kernel NULL pointer dereference by dlm_astd

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);
>
 

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