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netfilter: x_tables: fix int overflow in xt_alloc_table_info()

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syzkaller triggered OOM kills by passing ipt_replace.size = -1
to IPT_SO_SET_REPLACE. The root cause is that SMP_ALIGN() in
xt_alloc_table_info() causes int overflow and the size check passes
when it should not. SMP_ALIGN() is no longer needed leftover.

Remove SMP_ALIGN() call in xt_alloc_table_info().

Reported-by: syzbot+4396883fa8c4f64e0175@syzkaller.appspotmail.com
Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Dmitry Vyukov 2017-12-28 09:48:54 +01:00 committed by Pablo Neira Ayuso
parent d1616f07e8
commit 889c604fd0
1 changed files with 1 additions and 2 deletions
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3
net/netfilter/x_tables.c
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@ -39,7 +39,6 @@ MODULE_LICENSE("GPL");
MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
MODULE_DESCRIPTION("{ip,ip6,arp,eb}_tables backend module");
#define SMP_ALIGN(x) (((x) + SMP_CACHE_BYTES-1) & ~(SMP_CACHE_BYTES-1))
#define XT_PCPU_BLOCK_SIZE 4096
struct compat_delta {
@ -1000,7 +999,7 @@ struct xt_table_info *xt_alloc_table_info(unsigned int size)
return NULL;
/* Pedantry: prevent them from hitting BUG() in vmalloc.c --RR */
if ((SMP_ALIGN(size) >> PAGE_SHIFT) + 2 > totalram_pages)
if ((size >> PAGE_SHIFT) + 2 > totalram_pages)
return NULL;
info = kvmalloc(sz, GFP_KERNEL);