Messages in this thread Patch in this message | | | From | Khalid Masum <> | Subject | [PATCH v3] xfrm: Update ipcomp_scratches with NULL if not allocated | Date | Thu, 1 Sep 2022 10:03:07 +0600 |
| |
Currently if ipcomp_alloc_scratches() fails to allocate memory ipcomp_scratches holds obsolete address. So when we try to free the percpu scratches using ipcomp_free_scratches() it tries to vfree non existent vm area. Described below:
static void * __percpu *ipcomp_alloc_scratches(void) { ... scratches = alloc_percpu(void *); if (!scratches) return NULL; ipcomp_scratches does not know about this allocation failure. Therefore holding the old obsolete address. ... }
So when we free,
static void ipcomp_free_scratches(void) { ... scratches = ipcomp_scratches; Assigning obsolete addresses from ipcomp_scratches
if (!scratches) return;
for_each_possible_cpu(i) vfree(*per_cpu_ptr(scratches, i)); Trying to free non existent page, causing warning: trying to vfree existent vm area. ... }
Fix this breakage by: (1) Update ipcomp_scratches with NULL if the above mentioned allocation fails. (2) Update ipcomp_scrtches with NULL when scratches is freed
Reported-by: syzbot+5ec9bb042ddfe9644773@syzkaller.appspotmail.com Tested-by: syzbot+5ec9bb042ddfe9644773@syzkaller.appspotmail.com Signed-off-by: Khalid Masum <khalid.masum.92@gmail.com> --- Changes since v2: - Set ipcomp_scratches to NULL when scratches is freed. - Update commit message. - v2 Link: https://lore.kernel.org/lkml/20220831142938.5882-1-khalid.masum.92@gmail.com/
Changes since v1: - Instead of altering usercount, update ipcomp_scratches to NULL - Update commit message. - v1 Link: https://lore.kernel.org/lkml/20220831014126.6708-1-khalid.masum.92@gmail.com/
diff --git a/net/xfrm/xfrm_ipcomp.c b/net/xfrm/xfrm_ipcomp.c index cb40ff0ff28d..3774d07c5819 100644 --- a/net/xfrm/xfrm_ipcomp.c +++ b/net/xfrm/xfrm_ipcomp.c @@ -203,6 +203,7 @@ static void ipcomp_free_scratches(void) vfree(*per_cpu_ptr(scratches, i)); free_percpu(scratches); + ipcomp_scratches = NULL; } static void * __percpu *ipcomp_alloc_scratches(void) @@ -215,7 +216,7 @@ static void * __percpu *ipcomp_alloc_scratches(void) scratches = alloc_percpu(void *); if (!scratches) - return NULL; + return ipcomp_scratches = NULL; ipcomp_scratches = scratches;
| |