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Message-ID: <20240827084822.18785-1-amishin@t-argos.ru>
Date: Tue, 27 Aug 2024 11:48:22 +0300
From: Aleksandr Mishin <amishin@...rgos.ru>
To: Samuel Ortiz <sameo@...ux.intel.com>
CC: Aleksandr Mishin <amishin@...rgos.ru>, Krzysztof Kozlowski
<krzk@...nel.org>, <netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
<lvc-project@...uxtesting.org>
Subject: [PATCH v2] nfc: pn533: Add poll mod list filling check
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@...rgos.ru>
---
v2: Update comment message for a more detailed description of the problem
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 b19c39dcfbd9..e2bc67300a91 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));
--
2.30.2
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