From: Kees Cook keescook@chromium.org
commit 12d6c1d3a2ad0c199ec57c201cdc71e8e157a232 upstream.
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" davem@davemloft.net Cc: Eric Dumazet edumazet@google.com Cc: Jakub Kicinski kuba@kernel.org Cc: Paolo Abeni pabeni@redhat.com Cc: netdev@vger.kernel.org Cc: Greg Kroah-Hartman gregkh@linuxfoundation.org Cc: Nick Desaulniers ndesaulniers@google.com Cc: David Rientjes rientjes@google.com Acked-by: Vlastimil Babka vbabka@suse.cz Link: https://patchwork.kernel.org/project/netdevbpf/patch/20221021234713.you.031-... Signed-off-by: Kees Cook keescook@chromium.org Link: https://lore.kernel.org/r/20221025223811.up.360-kees@kernel.org Signed-off-by: Paolo Abeni pabeni@redhat.com Cc: Daniel Díaz daniel.diaz@linaro.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/core/skbuff.c | 52 ++++++++++++++++++++++++++-------------------------- 1 file changed, 26 insertions(+), 26 deletions(-)
--- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -506,14 +506,14 @@ struct sk_buff *__alloc_skb(unsigned int */ 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. + /* kmalloc_size_roundup() 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);
@@ -1822,10 +1822,11 @@ 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);
@@ -1833,15 +1834,16 @@ int pskb_expand_head(struct sk_buff *skb
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. @@ -6182,21 +6184,20 @@ static int pskb_carve_inside_header(stru 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); @@ -6301,22 +6302,21 @@ static int pskb_carve_inside_nonlinear(s 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]));