From cc1dfa8b7571ea16dec9a29e0f4c4cad90b2a761 Mon Sep 17 00:00:00 2001 From: Thomas Tai Date: Tue, 15 Aug 2017 11:54:09 -0500 Subject: [PATCH] gfs2: fix slab corruption during mounting and umounting gfs file system When using cman-3.0.12.1 and gfs2-utils-3.0.12.1, mounting and unmounting GFS2 file system would cause kernel to hang. The slab allocator suggests that it is likely a double free memory corruption. The issue is traced back to v3.9-rc6 where a patch is submitted to use kzalloc() for storing a bitmap instead of using a local variable. The intention is to allocate memory during mount and to free memory during unmount. The original patch misses a code path which has already freed the memory and caused memory corruption. This patch sets the memory pointer to NULL after the memory is freed, so that double free memory corruption will not happen. gdlm_mount() '-- set_recover_size() which use kzalloc() '-- if dlm does not support ops callbacks then '--- free_recover_size() which use kfree() gldm_unmount() '-- free_recover_size() which use kfree() Previous patch which introduced the double free issue is commit 57c7310b8eb9 ("GFS2: use kmalloc for lvb bitmap") Signed-off-by: Thomas Tai Signed-off-by: Bob Peterson Reviewed-by: Liam R. Howlett --- fs/gfs2/lock_dlm.c | 1 + 1 file changed, 1 insertion(+) diff --git a/fs/gfs2/lock_dlm.c b/fs/gfs2/lock_dlm.c index 0515f0a68637..1d98b8a36eb3 100644 --- a/fs/gfs2/lock_dlm.c +++ b/fs/gfs2/lock_dlm.c @@ -1059,6 +1059,7 @@ static void free_recover_size(struct lm_lockstruct *ls) ls->ls_recover_submit = NULL; ls->ls_recover_result = NULL; ls->ls_recover_size = 0; + ls->ls_lvb_bits = NULL; } /* dlm calls before it does lock recovery */