diff options
| author | Kees Cook <[email protected]> | 2020-08-06 23:18:24 -0700 |
|---|---|---|
| committer | Linus Torvalds <[email protected]> | 2020-08-07 11:33:22 -0700 |
| commit | dabc3e291d56e3125113101bc6d53d1a1738294d (patch) | |
| tree | b7184a61847d02a235d5d2dfbd6bc901f1d36b78 | |
| parent | 3404be67bf73515babd74acd8525d09dafe4234d (diff) | |
mm/slab: add naive detection of double free
Similar to commit ce6fa91b9363 ("mm/slub.c: add a naive detection of
double free or corruption"), add a very cheap double-free check for SLAB
under CONFIG_SLAB_FREELIST_HARDENED. With this added, the
"SLAB_FREE_DOUBLE" LKDTM test passes under SLAB:
lkdtm: Performing direct entry SLAB_FREE_DOUBLE
lkdtm: Attempting double slab free ...
------------[ cut here ]------------
WARNING: CPU: 2 PID: 2193 at mm/slab.c:757 ___cache _free+0x325/0x390
[[email protected]: fix misplaced __free_one()]
Link: http://lkml.kernel.org/r/202006261306.0D82A2B@keescook
Link: https://lore.kernel.org/lkml/[email protected]
Signed-off-by: Kees Cook <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Acked-by: Vlastimil Babka <[email protected]>
Acked-by: Randy Dunlap <[email protected]> [build tested]
Cc: Roman Gushchin <[email protected]>
Cc: Christoph Lameter <[email protected]>
Cc: Alexander Popov <[email protected]>
Cc: Pekka Enberg <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Joonsoo Kim <[email protected]>
Cc: Vinayak Menon <[email protected]>
Cc: Matthew Garrett <[email protected]>
Cc: Jann Horn <[email protected]>
Cc: Vijayanand Jitta <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Linus Torvalds <[email protected]>
| -rw-r--r-- | mm/slab.c | 14 |
1 files changed, 12 insertions, 2 deletions
diff --git a/mm/slab.c b/mm/slab.c index 9350062ffc1a..77e90f9de9c0 100644 --- a/mm/slab.c +++ b/mm/slab.c @@ -588,6 +588,16 @@ static int transfer_objects(struct array_cache *to, return nr; } +/* &alien->lock must be held by alien callers. */ +static __always_inline void __free_one(struct array_cache *ac, void *objp) +{ + /* Avoid trivial double-free. */ + if (IS_ENABLED(CONFIG_SLAB_FREELIST_HARDENED) && + WARN_ON_ONCE(ac->avail > 0 && ac->entry[ac->avail - 1] == objp)) + return; + ac->entry[ac->avail++] = objp; +} + #ifndef CONFIG_NUMA #define drain_alien_cache(cachep, alien) do { } while (0) @@ -767,7 +777,7 @@ static int __cache_free_alien(struct kmem_cache *cachep, void *objp, STATS_INC_ACOVERFLOW(cachep); __drain_alien_cache(cachep, ac, page_node, &list); } - ac->entry[ac->avail++] = objp; + __free_one(ac, objp); spin_unlock(&alien->lock); slabs_destroy(cachep, &list); } else { @@ -3466,7 +3476,7 @@ void ___cache_free(struct kmem_cache *cachep, void *objp, } } - ac->entry[ac->avail++] = objp; + __free_one(ac, objp); } /** |