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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id n21-20020a63ee55000000b00439d071c110sm13864837pgk.43.2022.10.21.16.49.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 21 Oct 2022 16:49:40 -0700 (PDT) From: Kees Cook To: "David S. Miller" Cc: Kees Cook , Eric Dumazet , Jakub Kicinski , Paolo Abeni , netdev@vger.kernel.org, Greg Kroah-Hartman , Nick Desaulniers , David Rientjes , Vlastimil Babka , Pavel Begunkov , Menglong Dong , linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: [PATCH v4] skbuff: Proactively round up to kmalloc bucket size Date: Fri, 21 Oct 2022 16:49:36 -0700 Message-Id: <20221021234713.you.031-kees@kernel.org> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=5254; h=from:subject:message-id; bh=mBqppqtvL2/WoVg/f5+5q7YdX/5rZQrDaP9jvq5SNds=; b=owEBbQKS/ZANAwAKAYly9N/cbcAmAcsmYgBjUzAQj4YnF7sfaNOXHp6h942Zp2pVBhavIZsxhufy hDpdcbqJAjMEAAEKAB0WIQSlw/aPIp3WD3I+bhOJcvTf3G3AJgUCY1MwEAAKCRCJcvTf3G3AJlswD/ 9Y3r9CwzM02Mmy50J+PYZcLUgI4ibXyNuMNwupIkwi6KUI2W9fvMVSawsAkM5b/x+M1CWBOI0Y8Koe YtS6rlW11Th17D7xxNhqDh2MViFxJSFl9x1j5zs7OR895024SdmRLS/eT+GonMGTWn65cJoNCutmED 7tuxvlsf4mYqHJkQT/f6ewQ18P9JVGQhhu+aR1dFaiEAHE/2WuZflnqMP6crdv/DEfH2pc6kwKXjy/ 97qL1b2eKrjXbKQX3EydGxGUPRVD0ceddrFUGftCdz0J2H4sZHhFMCQRzbcCrJDNSiAAIVqdbyvrvI Jt+jYK4+8/K5qUobuq2jd85Yrp9gyfx7TX5TmMMWPq9ylU3VD8rCk3x//Wcf0+gJH8QzVFEbPas4OS XK8PyLEgI+uqZZhyHZCbo1hND4yu4lSZfeoRYp3nn3vyqOzaX6+CAPOJUD7+Yl4FSBZZa2EwDVkwKe FfNAS6xx79PI5Fvkyu2+hz6JPiOauASQTiFUe9wC/G+drcJFepnqlm8uPEqlCf02NGzyRrQUnkzDL7 rCEZs2bEF/laMbAR8K1Jq6vke2ET07GdEDOYiheaSE0SM6XfAq5rcn9hTReprIdJWKY6qJsB6986Qv nkOewbajlHJi/78QLUwtnxa+p096QwNqqhJpAAolsFrvQVy2XY5vLah1Snnw== X-Developer-Key: i=keescook@chromium.org; a=openpgp; fpr=A5C3F68F229DD60F723E6E138972F4DFDC6DC026 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Instead of discovering the kmalloc bucket size _after_ allocation, round up proactively so the allocation is explicitly made for the full size, allowing the compiler to correctly reason about the resulting size of the buffer through the existing __alloc_size() hint. This will allow for kernels built with CONFIG_UBSAN_BOUNDS or the coming dynamic bounds checking under CONFIG_FORTIFY_SOURCE to gain back the __alloc_size() hints that were temporarily reverted in commit 93dd04ab0b2b ("slab: remove __alloc_size attribute from __kmalloc_track_caller") Cc: "David S. Miller" Cc: Eric Dumazet Cc: Jakub Kicinski Cc: Paolo Abeni Cc: netdev@vger.kernel.org Cc: Greg Kroah-Hartman Cc: Nick Desaulniers Cc: David Rientjes Cc: Vlastimil Babka Signed-off-by: Kees Cook --- v4: use kmalloc_size_roundup() in callers, not kmalloc_reserve() v3: https://lore.kernel.org/lkml/20221018093005.give.246-kees@kernel.org v2: https://lore.kernel.org/lkml/20220923202822.2667581-4-keescook@chromium.org --- net/core/skbuff.c | 50 +++++++++++++++++++++++------------------------ 1 file changed, 25 insertions(+), 25 deletions(-) diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 651a82d30b09..77af430296e2 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -508,14 +508,14 @@ struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask, */ size = SKB_DATA_ALIGN(size); size += SKB_DATA_ALIGN(sizeof(struct skb_shared_info)); - data = kmalloc_reserve(size, gfp_mask, node, &pfmemalloc); + osize = kmalloc_size_roundup(size); + data = kmalloc_reserve(osize, gfp_mask, node, &pfmemalloc); if (unlikely(!data)) goto nodata; /* kmalloc(size) might give us more room than requested. * Put skb_shared_info exactly at the end of allocated zone, * to allow max possible filling before reallocation. */ - osize = ksize(data); size = SKB_WITH_OVERHEAD(osize); prefetchw(data + size); @@ -1816,10 +1816,11 @@ EXPORT_SYMBOL(__pskb_copy_fclone); int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail, gfp_t gfp_mask) { - int i, osize = skb_end_offset(skb); - int size = osize + nhead + ntail; + unsigned int osize = skb_end_offset(skb); + unsigned int size = osize + nhead + ntail; long off; u8 *data; + int i; BUG_ON(nhead < 0); @@ -1827,15 +1828,16 @@ int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail, skb_zcopy_downgrade_managed(skb); - size = SKB_DATA_ALIGN(size); - if (skb_pfmemalloc(skb)) gfp_mask |= __GFP_MEMALLOC; - data = kmalloc_reserve(size + SKB_DATA_ALIGN(sizeof(struct skb_shared_info)), - gfp_mask, NUMA_NO_NODE, NULL); + + size = SKB_DATA_ALIGN(size); + size += SKB_DATA_ALIGN(sizeof(struct skb_shared_info)); + size = kmalloc_size_roundup(size); + data = kmalloc_reserve(size, gfp_mask, NUMA_NO_NODE, NULL); if (!data) goto nodata; - size = SKB_WITH_OVERHEAD(ksize(data)); + size = SKB_WITH_OVERHEAD(size); /* Copy only real data... and, alas, header. This should be * optimized for the cases when header is void. @@ -6169,21 +6171,20 @@ static int pskb_carve_inside_header(struct sk_buff *skb, const u32 off, const int headlen, gfp_t gfp_mask) { int i; - int size = skb_end_offset(skb); + unsigned int size = skb_end_offset(skb); int new_hlen = headlen - off; u8 *data; - size = SKB_DATA_ALIGN(size); - if (skb_pfmemalloc(skb)) gfp_mask |= __GFP_MEMALLOC; - data = kmalloc_reserve(size + - SKB_DATA_ALIGN(sizeof(struct skb_shared_info)), - gfp_mask, NUMA_NO_NODE, NULL); + + size = SKB_DATA_ALIGN(size); + size += SKB_DATA_ALIGN(sizeof(struct skb_shared_info)); + size = kmalloc_size_roundup(size); + data = kmalloc_reserve(size, gfp_mask, NUMA_NO_NODE, NULL); if (!data) return -ENOMEM; - - size = SKB_WITH_OVERHEAD(ksize(data)); + size = SKB_WITH_OVERHEAD(size); /* Copy real data, and all frags */ skb_copy_from_linear_data_offset(skb, off, data, new_hlen); @@ -6288,22 +6289,21 @@ static int pskb_carve_inside_nonlinear(struct sk_buff *skb, const u32 off, int pos, gfp_t gfp_mask) { int i, k = 0; - int size = skb_end_offset(skb); + unsigned int size = skb_end_offset(skb); u8 *data; const int nfrags = skb_shinfo(skb)->nr_frags; struct skb_shared_info *shinfo; - size = SKB_DATA_ALIGN(size); - if (skb_pfmemalloc(skb)) gfp_mask |= __GFP_MEMALLOC; - data = kmalloc_reserve(size + - SKB_DATA_ALIGN(sizeof(struct skb_shared_info)), - gfp_mask, NUMA_NO_NODE, NULL); + + size = SKB_DATA_ALIGN(size); + size += SKB_DATA_ALIGN(sizeof(struct skb_shared_info)); + size = kmalloc_size_roundup(size); + data = kmalloc_reserve(size, gfp_mask, NUMA_NO_NODE, NULL); if (!data) return -ENOMEM; - - size = SKB_WITH_OVERHEAD(ksize(data)); + size = SKB_WITH_OVERHEAD(size); memcpy((struct skb_shared_info *)(data + size), skb_shinfo(skb), offsetof(struct skb_shared_info, frags[0])); -- 2.34.1