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 <[email protected]> > 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); >
