octeontx2-af: avoid off-by-one read from userspace

[ Upstream commit f299ee709fb45036454ca11e90cb2810fe771878 ]

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>
Link: https://lore.kernel.org/r/20240424-fix-oob-read-v2-6-f1f1b53a10f4@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/net/ethernet/marvell/octeontx2/af/rvu_debugfs.c b/drivers/net/ethernet/marvell/octeontx2/af/rvu_debugfs.c
index e6d7914ce61c4e8019b8b05edb0a49d810c77eb5..e7eca8141e8c765736a13bf56924d8d3d786cb5b 100644 (file)
--- 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';