[PATCH] video: fbdev: metronomefb: Fix buffer overflow in load_waveform()

[Suraj Sonawane]

Fix an error detected by the Smatch tool:

drivers/video/fbdev/metronomefb.c:220 load_waveform() error:
buffer overflow 'wfm_hdr->stuff2a' 2 <= 4
drivers/video/fbdev/metronomefb.c:220 load_waveform() error:
buffer overflow 'wfm_hdr->stuff2a' 2 <= 4

The access to wfm_hdr->stuff2a in the loop can lead to a buffer
overflow if stuff2a is not large enough. To fix this, a check was
added to ensure that stuff2a has sufficient space before accessing
it. This prevents the overflow and improves the safety of the code.

Signed-off-by: Suraj Sonawane <surajsonawane0215 at gmail.com>
---
 drivers/video/fbdev/metronomefb.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/video/fbdev/metronomefb.c b/drivers/video/fbdev/metronomefb.c
index 6f0942c6e..9da55cef2 100644
--- a/drivers/video/fbdev/metronomefb.c
+++ b/drivers/video/fbdev/metronomefb.c
@@ -210,6 +210,12 @@ static int load_waveform(u8 *mem, size_t size, int m, int t,
 	}
 	wfm_hdr->mc += 1;
 	wfm_hdr->trc += 1;
+
+	if (sizeof(wfm_hdr->stuff2a) < 5) {
+		dev_err(dev, "Error: insufficient space in stuff2a\n");
+		return -EINVAL;
+	}
+
 	for (i = 0; i < 5; i++) {
 		if (*(wfm_hdr->stuff2a + i) != 0) {
 			dev_err(dev, "Error: unexpected value in padding\n");
-- 
2.34.1