net: expand textsearch ts_state to fit skb_seq_state
The referenced commit expands the skb_seq_state used by skb_find_text with a 4B frag_off field, growing it to 48B. This exceeds container ts_state->cb, causing a stack corruption: [ 73.238353] Kernel panic - not syncing: stack-protector: Kernel stack is corrupted in: skb_find_text+0xc5/0xd0 [ 73.247384] CPU: 1 PID: 376 Comm: nping Not tainted 5.11.0+ #4 [ 73.252613] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-2 04/01/2014 [ 73.260078] Call Trace: [ 73.264677] dump_stack+0x57/0x6a [ 73.267866] panic+0xf6/0x2b7 [ 73.270578] ? skb_find_text+0xc5/0xd0 [ 73.273964] __stack_chk_fail+0x10/0x10 [ 73.277491] skb_find_text+0xc5/0xd0 [ 73.280727] string_mt+0x1f/0x30 [ 73.283639] ipt_do_table+0x214/0x410 The struct is passed between skb_find_text and its callbacks skb_prepare_seq_read, skb_seq_read and skb_abort_seq read through the textsearch interface using TS_SKB_CB. I assumed that this mapped to skb->cb like other .._SKB_CB wrappers. skb->cb is 48B. But it maps to ts_state->cb, which is only 40B. skb->cb was increased from 40B to 48B after ts_state was introduced, in commit 3e3850e9 ("[NETFILTER]: Fix xfrm lookup in ip_route_me_harder/ip6_route_me_harder"). Increase ts_state.cb[] to 48 to fit the struct. Also add a BUILD_BUG_ON to avoid a repeat. The alternative is to directly add a dependency from textsearch onto linux/skbuff.h, but I think the intent is textsearch to have no such dependencies on its callers. Link: https://bugzilla.kernel.org/show_bug.cgi?id=211911 Fixes: 97550f6f ("net: compound page support in skb_seq_read") Reported-by:Kris Karas <bugs-a17@moonlit-rail.com> Signed-off-by:
Willem de Bruijn <willemb@google.com> Signed-off-by:
David S. Miller <davem@davemloft.net>
parent
2353db75
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