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[v2,6/6] octeontx2-af: avoid off-by-one read from userspace

Message ID 20240424-fix-oob-read-v2-6-f1f1b53a10f4@gmail.com (mailing list archive)
State Accepted
Headers show
Series Ensure the copied buf is NUL terminated | expand

Commit Message

Bui Quang Minh April 24, 2024, 2:44 p.m. UTC 
We try to access count + 1 byte from userspace with memdup_user(buffer,
count + 1). However, the userspace only provides buffer of count bytes and
only these count bytes are verified to be okay to access. To ensure the
copied buffer is NUL terminated, we use memdup_user_nul instead.

Fixes: 3a2eb515d136 ("octeontx2-af: Fix an off by one in rvu_dbg_qsize_write()")
Signed-off-by: Bui Quang Minh <minhquangbui99@gmail.com>
---
 drivers/net/ethernet/marvell/octeontx2/af/rvu_debugfs.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)
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Patch

diff --git a/drivers/net/ethernet/marvell/octeontx2/af/rvu_debugfs.c b/drivers/net/ethernet/marvell/octeontx2/af/rvu_debugfs.c
index 2500f5ba4f5a..881d704644fb 100644
--- a/drivers/net/ethernet/marvell/octeontx2/af/rvu_debugfs.c
+++ b/drivers/net/ethernet/marvell/octeontx2/af/rvu_debugfs.c
@@ -999,12 +999,10 @@  static ssize_t rvu_dbg_qsize_write(struct file *filp,
 	u16 pcifunc;
 	int ret, lf;
 
-	cmd_buf = memdup_user(buffer, count + 1);
+	cmd_buf = memdup_user_nul(buffer, count);
 	if (IS_ERR(cmd_buf))
 		return -ENOMEM;
 
-	cmd_buf[count] = '\0';
-
 	cmd_buf_tmp = strchr(cmd_buf, '\n');
 	if (cmd_buf_tmp) {
 		*cmd_buf_tmp = '\0';