diff options
| author | Pekka Enberg <penberg@cs.helsinki.fi> | 2008-07-26 17:49:33 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2008-07-26 17:49:33 -0700 |
| commit | 93bc4e89c260d91576840c4881d1066d84ccd422 (patch) | |
| tree | 456176a054fc9a3fed18ac6ce50c7a34a86c5808 | |
| parent | 3918fed5f31213067c1c345bd904e1ea369e6819 (diff) | |
netfilter: fix double-free and use-after free
As suggested by Patrick McHardy, introduce a __krealloc() that doesn't
free the original buffer to fix a double-free and use-after-free bug
introduced by me in netfilter that uses RCU.
Reported-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
Tested-by: Dieter Ries <clip2@gmx.de>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | include/linux/slab.h | 1 | ||||
| -rw-r--r-- | mm/util.c | 44 | ||||
| -rw-r--r-- | net/netfilter/nf_conntrack_extend.c | 2 |
3 files changed, 36 insertions, 11 deletions
diff --git a/include/linux/slab.h b/include/linux/slab.h index 9aa90a6f20e0..be6f1d40b66a 100644 --- a/include/linux/slab.h +++ b/include/linux/slab.h @@ -96,6 +96,7 @@ int kmem_ptr_validate(struct kmem_cache *cachep, const void *ptr); /* * Common kmalloc functions provided by all allocators */ +void * __must_check __krealloc(const void *, size_t, gfp_t); void * __must_check krealloc(const void *, size_t, gfp_t); void kfree(const void *); size_t ksize(const void *); diff --git a/mm/util.c b/mm/util.c index 8f18683825bc..6ef9e9943f62 100644 --- a/mm/util.c +++ b/mm/util.c @@ -68,25 +68,22 @@ void *kmemdup(const void *src, size_t len, gfp_t gfp) EXPORT_SYMBOL(kmemdup); /** - * krealloc - reallocate memory. The contents will remain unchanged. + * __krealloc - like krealloc() but don't free @p. * @p: object to reallocate memory for. * @new_size: how many bytes of memory are required. * @flags: the type of memory to allocate. * - * The contents of the object pointed to are preserved up to the - * lesser of the new and old sizes. If @p is %NULL, krealloc() - * behaves exactly like kmalloc(). If @size is 0 and @p is not a - * %NULL pointer, the object pointed to is freed. + * This function is like krealloc() except it never frees the originally + * allocated buffer. Use this if you don't want to free the buffer immediately + * like, for example, with RCU. */ -void *krealloc(const void *p, size_t new_size, gfp_t flags) +void *__krealloc(const void *p, size_t new_size, gfp_t flags) { void *ret; size_t ks = 0; - if (unlikely(!new_size)) { - kfree(p); + if (unlikely(!new_size)) return ZERO_SIZE_PTR; - } if (p) ks = ksize(p); @@ -95,10 +92,37 @@ void *krealloc(const void *p, size_t new_size, gfp_t flags) return (void *)p; ret = kmalloc_track_caller(new_size, flags); - if (ret && p) { + if (ret && p) memcpy(ret, p, ks); + + return ret; +} +EXPORT_SYMBOL(__krealloc); + +/** + * krealloc - reallocate memory. The contents will remain unchanged. + * @p: object to reallocate memory for. + * @new_size: how many bytes of memory are required. + * @flags: the type of memory to allocate. + * + * The contents of the object pointed to are preserved up to the + * lesser of the new and old sizes. If @p is %NULL, krealloc() + * behaves exactly like kmalloc(). If @size is 0 and @p is not a + * %NULL pointer, the object pointed to is freed. + */ +void *krealloc(const void *p, size_t new_size, gfp_t flags) +{ + void *ret; + + if (unlikely(!new_size)) { kfree(p); + return ZERO_SIZE_PTR; } + + ret = __krealloc(p, new_size, flags); + if (ret && p != ret) + kfree(p); + return ret; } EXPORT_SYMBOL(krealloc); diff --git a/net/netfilter/nf_conntrack_extend.c b/net/netfilter/nf_conntrack_extend.c index 3469bc71a385..c956ef7eeecb 100644 --- a/net/netfilter/nf_conntrack_extend.c +++ b/net/netfilter/nf_conntrack_extend.c @@ -95,7 +95,7 @@ void *__nf_ct_ext_add(struct nf_conn *ct, enum nf_ct_ext_id id, gfp_t gfp) newlen = newoff + t->len; rcu_read_unlock(); - new = krealloc(ct->ext, newlen, gfp); + new = __krealloc(ct->ext, newlen, gfp); if (!new) return NULL; |