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Subject[PATCH AUTOSEL for 4.9 149/190] ath10k: fix out of bounds access to local buffer
Date
From: Michael Mera <dev@michaelmera.com>

[ Upstream commit a16703aaeaedec7a8bee5be5522c7c3e75478951 ]

During write to debugfs file simulate_fw_crash, fixed-size local buffer
'buf' is accessed and modified at index 'count-1', where 'count' is the
size of the write (so potentially out of bounds).
This patch fixes this problem.

Signed-off-by: Michael Mera <dev@michaelmera.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
drivers/net/wireless/ath/ath10k/debug.c | 16 ++++++++++------
1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/net/wireless/ath/ath10k/debug.c b/drivers/net/wireless/ath/ath10k/debug.c
index 82a4c67f3672..4b3e70df223e 100644
--- a/drivers/net/wireless/ath/ath10k/debug.c
+++ b/drivers/net/wireless/ath/ath10k/debug.c
@@ -624,17 +624,21 @@ static ssize_t ath10k_write_simulate_fw_crash(struct file *file,
size_t count, loff_t *ppos)
{
struct ath10k *ar = file->private_data;
- char buf[32];
+ char buf[32] = {0};
+ ssize_t rc;
int ret;

- simple_write_to_buffer(buf, sizeof(buf) - 1, ppos, user_buf, count);
+ /* filter partial writes and invalid commands */
+ if (*ppos != 0 || count >= sizeof(buf) || count == 0)
+ return -EINVAL;

- /* make sure that buf is null terminated */
- buf[sizeof(buf) - 1] = 0;
+ rc = simple_write_to_buffer(buf, sizeof(buf) - 1, ppos, user_buf, count);
+ if (rc < 0)
+ return rc;

/* drop the possible '\n' from the end */
- if (buf[count - 1] == '\n')
- buf[count - 1] = 0;
+ if (buf[*ppos - 1] == '\n')
+ buf[*ppos - 1] = '\0';

mutex_lock(&ar->conf_mutex);

--
2.14.1
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