From b1becbdee776b447f203aa8da9a40488d5a75e1d Mon Sep 17 00:00:00 2001 From: Bob Peterson Date: Thu, 17 Jun 2010 16:45:37 -0400 Subject: [PATCH] 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 Signed-off-by: Steven Whitehouse --- fs/gfs2/inode.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/fs/gfs2/inode.c b/fs/gfs2/inode.c index b5612cbb62a5..f03afd9c44bc 100644 --- a/fs/gfs2/inode.c +++ b/fs/gfs2/inode.c @@ -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); -- 2.30.2