6.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Aleksandr Mishin <amishin@xxxxxxxxxx>
[ Upstream commit febccb39255f9df35527b88c953b2e0deae50e53 ]
In case of im_protocols value is 1 and tm_protocols value is 0 this
combination successfully passes the check
'if (!im_protocols && !tm_protocols)' in the nfc_start_poll().
But then after pn533_poll_create_mod_list() call in pn533_start_poll()
poll mod list will remain empty and dev->poll_mod_count will remain 0
which lead to division by zero.
Normally no im protocol has value 1 in the mask, so this combination is
not expected by driver. But these protocol values actually come from
userspace via Netlink interface (NFC_CMD_START_POLL operation). So a
broken or malicious program may pass a message containing a "bad"
combination of protocol parameter values so that dev->poll_mod_count
is not incremented inside pn533_poll_create_mod_list(), thus leading
to division by zero.
Call trace looks like:
nfc_genl_start_poll()
nfc_start_poll()
->start_poll()
pn533_start_poll()
Add poll mod list filling check.
Found by Linux Verification Center (linuxtesting.org) with SVACE.
Fixes: dfccd0f58044 ("NFC: pn533: Add some polling entropy")
Signed-off-by: Aleksandr Mishin <amishin@xxxxxxxxxx>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxx>
Link: https://patch.msgid.link/20240827084822.18785-1-amishin@xxxxxxxxxx
Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/nfc/pn533/pn533.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/drivers/nfc/pn533/pn533.c b/drivers/nfc/pn533/pn533.c
index b19c39dcfbd93..e2bc67300a915 100644
--- a/drivers/nfc/pn533/pn533.c
+++ b/drivers/nfc/pn533/pn533.c
@@ -1723,6 +1723,11 @@ static int pn533_start_poll(struct nfc_dev *nfc_dev,
}
pn533_poll_create_mod_list(dev, im_protocols, tm_protocols);
+ if (!dev->poll_mod_count) {
+ nfc_err(dev->dev,
+ "Poll mod list is empty\n");
+ return -EINVAL;
+ }
/* Do not always start polling from the same modulation */
get_random_bytes(&rand_mod, sizeof(rand_mod));
--
2.43.0
