[PATCH 1/4] fbdev: imsttfb: Fix error handling in init_imstt()

[Markus Elfring]

From: Markus Elfring <elfring at users.sourceforge.net>
Date: Tue, 23 May 2023 14:32:39 +0200

The return value was overlooked from a call of
the function “fb_alloc_cmap”.

* Thus use a corresponding error check.

* Add two jump targets so that a bit of exception handling
  can be better reused at the end of this function.


Reported-by: Helge Deller <deller at gmx.de>
Link: https://lore.kernel.org/dri-devel/069f2f78-01f3-9476-d860-2b695c122649@gmx.de/
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Fixes: c75f5a550610 ("fbdev: imsttfb: Fix use after free bug in imsttfb_probe")
Signed-off-by: Markus Elfring <elfring at users.sourceforge.net>
---
 drivers/video/fbdev/imsttfb.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/drivers/video/fbdev/imsttfb.c b/drivers/video/fbdev/imsttfb.c
index 975dd682fae4..d3532def4707 100644
--- a/drivers/video/fbdev/imsttfb.c
+++ b/drivers/video/fbdev/imsttfb.c
@@ -1351,6 +1351,7 @@ static int init_imstt(struct fb_info *info)
 {
 	struct imstt_par *par = info->par;
 	__u32 i, tmp, *ip, *end;
+	int ret;

 	tmp = read_reg_le32(par->dc_regs, PRC);
 	if (par->ramdac == IBM)
@@ -1419,8 +1420,7 @@ static int init_imstt(struct fb_info *info)
 	if ((info->var.xres * info->var.yres) * (info->var.bits_per_pixel >> 3) > info->fix.smem_len
 	    || !(compute_imstt_regvals(par, info->var.xres, info->var.yres))) {
 		printk("imsttfb: %ux%ux%u not supported\n", info->var.xres, info->var.yres, info->var.bits_per_pixel);
-		framebuffer_release(info);
-		return -ENODEV;
+		goto e_nodev;
 	}

 	sprintf(info->fix.id, "IMS TT (%s)", par->ramdac == IBM ? "IBM" : "TVP");
@@ -1452,17 +1452,25 @@ static int init_imstt(struct fb_info *info)
 	              FBINFO_HWACCEL_FILLRECT |
 	              FBINFO_HWACCEL_YPAN;

-	fb_alloc_cmap(&info->cmap, 0, 0);
+	ret = fb_alloc_cmap(&info->cmap, 0, 0);
+	if (ret)
+		goto release_framebuffer;

 	if (register_framebuffer(info) < 0) {
-		framebuffer_release(info);
-		return -ENODEV;
+		fb_dealloc_cmap(&info->cmap);
+		goto e_nodev;
 	}

 	tmp = (read_reg_le32(par->dc_regs, SSTATUS) & 0x0f00) >> 8;
 	fb_info(info, "%s frame buffer; %uMB vram; chip version %u\n",
 		info->fix.id, info->fix.smem_len >> 20, tmp);
 	return 0;
+
+e_nodev:
+	ret = -ENODEV;
+release_framebuffer:
+	framebuffer_release(info);
+	return ret;
 }

 static int imsttfb_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
--
2.40.1