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| author | Eric Dumazet <eric.dumazet@gmail.com> | 2011-12-13 04:57:06 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2012-02-20 12:48:14 -0800 |
| commit | 16c7560fcca939095d099da4316f2df66aebc3ba (patch) | |
| tree | 62c6ca33a6d17069cc9028ecce53e18a87526618 | |
| parent | d3a6a79cfe7641d797ab74eea55b93e0f35f66d7 (diff) | |
| download | lwn-16c7560fcca939095d099da4316f2df66aebc3ba.tar.gz lwn-16c7560fcca939095d099da4316f2df66aebc3ba.zip | |
slub: fix a possible memleak in __slab_alloc()
commit 73736e0387ba0e6d2b703407b4d26168d31516a7 upstream.
Zhihua Che reported a possible memleak in slub allocator on
CONFIG_PREEMPT=y builds.
It is possible current thread migrates right before disabling irqs in
__slab_alloc(). We must check again c->freelist, and perform a normal
allocation instead of scratching c->freelist.
Many thanks to Zhihua Che for spotting this bug, introduced in 2.6.39
V2: Its also possible an IRQ freed one (or several) object(s) and
populated c->freelist, so its not a CONFIG_PREEMPT only problem.
Reported-by: Zhihua Che <zhihua.che@gmail.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | mm/slub.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/mm/slub.c b/mm/slub.c index 35f351f26193..0d0901ebaea2 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -1818,6 +1818,11 @@ static void *__slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, if (unlikely(!node_match(c, node))) goto another_slab; + /* must check again c->freelist in case of cpu migration or IRQ */ + object = c->freelist; + if (object) + goto update_freelist; + stat(s, ALLOC_REFILL); load_freelist: @@ -1827,6 +1832,7 @@ load_freelist: if (kmem_cache_debug(s)) goto debug; +update_freelist: c->freelist = get_freepointer(s, object); page->inuse = page->objects; page->freelist = NULL; |