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[net,3/3] sch_cake: Fix out of bounds when parsing TCP options

Message ID 20210609142212.3096691-4-maximmi@nvidia.com
State New
Headers show
Series Fix out of bounds when parsing TCP options | expand

Commit Message

Maxim Mikityanskiy June 9, 2021, 2:22 p.m. UTC 
The TCP option parser in cake qdisc (cake_get_tcpopt and
cake_tcph_may_drop) could read one byte out of bounds. When the length
is 1, the execution flow gets into the loop, reads one byte of the
opcode, and if the opcode is neither TCPOPT_EOL nor TCPOPT_NOP, it reads
one more byte, which exceeds the length of 1.

This fix is inspired by commit 9609dad263f8 ("ipv4: tcp_input: fix stack
out of bounds when parsing TCP options.").

Cc: Young Xiao <92siuyang@gmail.com>
Fixes: 8b7138814f29 ("sch_cake: Add optional ACK filter")
Signed-off-by: Maxim Mikityanskiy <maximmi@nvidia.com>
---
 net/sched/sch_cake.c | 4 ++++
 1 file changed, 4 insertions(+)
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Patch

diff --git a/net/sched/sch_cake.c b/net/sched/sch_cake.c
index 7d37638ee1c7..6b03eebf0a78 100644
--- a/net/sched/sch_cake.c
+++ b/net/sched/sch_cake.c
@@ -967,6 +967,8 @@  static const void *cake_get_tcpopt(const struct tcphdr *tcph,
 			length--;
 			continue;
 		}
+		if (length < 2)
+			break;
 		opsize = *ptr++;
 		if (opsize < 2 || opsize > length)
 			break;
@@ -1104,6 +1106,8 @@  static bool cake_tcph_may_drop(const struct tcphdr *tcph,
 			length--;
 			continue;
 		}
+		if (length < 2)
+			break;
 		opsize = *ptr++;
 		if (opsize < 2 || opsize > length)
 			break;