On 04/18/2017 04:54 PM, Andrey Konovalov wrote: > Hi, > > I've got the following error report while fuzzing the kernel with syzkaller. > > On commit 4f7d029b9bf009fbee76bb10c0c4351a1870d2f3 (4.11-rc7). > > A reproducer and .config are attached. > > ================================================================== > BUG: KASAN: slab-out-of-bounds in seg6_validate_srh+0x203/0x220 > net/ipv6/seg6.c:57 at addr ffff88006a759608 > Read of size 1 by task syz-executor4/2627
Thanks for the report. It seems to happen when the trailing data is less than sizeof(struct sr6_tlv). The following (untested) patch should fix the issue, I'll test it and submit it properly if it works. diff --git a/net/ipv6/seg6.c b/net/ipv6/seg6.c index a855eb3..5f44ffe 100644 --- a/net/ipv6/seg6.c +++ b/net/ipv6/seg6.c @@ -53,6 +53,9 @@ bool seg6_validate_srh(struct ipv6_sr_hdr *srh, int len) struct sr6_tlv *tlv; unsigned int tlv_len; + if (trailing < sizeof(*tlv)) + return false; + tlv = (struct sr6_tlv *)((unsigned char *)srh + tlv_offset); tlv_len = sizeof(*tlv) + tlv->len;
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