6.12-stable review patch. If anyone has any objections, please let me know.
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From: Junrui Luo moonafterrain@outlook.com
[ Upstream commit 8a11ff0948b5ad09b71896b7ccc850625f9878d1 ]
The cffrml_receive() function extracts a length field from the packet header and, when FCS is disabled, subtracts 2 from this length without validating that len >= 2.
If an attacker sends a malicious packet with a length field of 0 or 1 to an interface with FCS disabled, the subtraction causes an integer underflow.
This can lead to memory exhaustion and kernel instability, potential information disclosure if padding contains uninitialized kernel memory.
Fix this by validating that len >= 2 before performing the subtraction.
Reported-by: Yuhao Jiang danisjiang@gmail.com Reported-by: Junrui Luo moonafterrain@outlook.com Fixes: b482cd2053e3 ("net-caif: add CAIF core protocol stack") Signed-off-by: Junrui Luo moonafterrain@outlook.com Reviewed-by: Simon Horman horms@kernel.org Link: https://patch.msgid.link/SYBPR01MB7881511122BAFEA8212A1608AFA6A@SYBPR01MB788... Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/caif/cffrml.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/net/caif/cffrml.c b/net/caif/cffrml.c index 6651a8dc62e04..d4d63586053ad 100644 --- a/net/caif/cffrml.c +++ b/net/caif/cffrml.c @@ -92,8 +92,15 @@ static int cffrml_receive(struct cflayer *layr, struct cfpkt *pkt) len = le16_to_cpu(tmp);
/* Subtract for FCS on length if FCS is not used. */ - if (!this->dofcs) + if (!this->dofcs) { + if (len < 2) { + ++cffrml_rcv_error; + pr_err("Invalid frame length (%d)\n", len); + cfpkt_destroy(pkt); + return -EPROTO; + } len -= 2; + }
if (cfpkt_setlen(pkt, len) < 0) { ++cffrml_rcv_error;