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From: Badhri Jagan Sridharan <badhri@google.com>
To: gregkh@linuxfoundation.org, heikki.krogerus@linux.intel.com
Cc: linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
	rdbabiera@google.com, stable@vger.kernel.org,
	Badhri Jagan Sridharan <badhri@google.com>
Subject: [PATCH v1] usb: typec: altmodes/displayport: fix pin_assignment_show
Date: Mon,  8 May 2023 21:44:43 +0000	[thread overview]
Message-ID: <20230508214443.893436-1-badhri@google.com> (raw)

This patch fixes negative indexing of buf array in pin_assignment_show
when get_current_pin_assignments returns 0 i.e. no compatible pin
assignments are found.

BUG: KASAN: use-after-free in pin_assignment_show+0x26c/0x33c
...
Call trace:
dump_backtrace+0x110/0x204
dump_stack_lvl+0x84/0xbc
print_report+0x358/0x974
kasan_report+0x9c/0xfc
__do_kernel_fault+0xd4/0x2d4
do_bad_area+0x48/0x168
do_tag_check_fault+0x24/0x38
do_mem_abort+0x6c/0x14c
el1_abort+0x44/0x68
el1h_64_sync_handler+0x64/0xa4
el1h_64_sync+0x78/0x7c
pin_assignment_show+0x26c/0x33c
dev_attr_show+0x50/0xc0

Fixes: 0e3bb7d6894d ("usb: typec: Add driver for DisplayPort alternate mode")
Cc: stable@vger.kernel.org
Signed-off-by: Badhri Jagan Sridharan <badhri@google.com>
---
 drivers/usb/typec/altmodes/displayport.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/usb/typec/altmodes/displayport.c b/drivers/usb/typec/altmodes/displayport.c
index 8f3e884222ad..66de880b28d0 100644
--- a/drivers/usb/typec/altmodes/displayport.c
+++ b/drivers/usb/typec/altmodes/displayport.c
@@ -516,6 +516,10 @@ static ssize_t pin_assignment_show(struct device *dev,
 
 	mutex_unlock(&dp->lock);
 
+	/* get_current_pin_assignments can return 0 when no matching pin assignments are found */
+	if (len == 0)
+		len++;
+
 	buf[len - 1] = '\n';
 	return len;
 }

base-commit: ac9a78681b921877518763ba0e89202254349d1b
-- 
2.40.1.521.gf1e218fcd8-goog


             reply	other threads:[~2023-05-08 21:45 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-05-08 21:44 Badhri Jagan Sridharan [this message]
2023-05-09 12:20 ` [PATCH v1] usb: typec: altmodes/displayport: fix pin_assignment_show Heikki Krogerus

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