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fbdev: sm501fb: Fix buffer errors in OF binding code

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The code that gets the frame buffer mode from OF has 'use after free',
'buffer overrun' and memory leaks.

info->edid_data isn't free if the probe functions fail or if
pd->def_mode is set.

If both the CRT and PANEL are enabled info->edid_data is used after
being freed and is freed twice.

The string returned by of_get_property(np, "mode", &len) is just
written over either the static "640x480-16@60" or the module parameter
string without any regard for the length (which is most likely longer).

Use kstrump() for the OF mode and free everything before freeing 'info.

Fixes: 4295f9bf74 ("video, sm501: add OF binding to support SM501")
Signed-off-by: David Laight <david.laight.linux@gmail.com>
Signed-off-by: Helge Deller <deller@gmx.de>
This commit is contained in:
David Laight
2026-06-08 13:42:42 +01:00
committed by Helge Deller
parent f5c147fda9
commit d8421e0938
1 changed files with 12 additions and 4 deletions
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16
drivers/video/fbdev/sm501fb.c
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@@ -96,6 +96,7 @@ struct sm501fb_info {
void __iomem *fbmem; /* remapped framebuffer */
size_t fbmem_len; /* length of remapped region */
u8 *edid_data;
char *fb_mode;
};
/* per-framebuffer private data */
@@ -1793,12 +1794,11 @@ static int sm501fb_init_fb(struct fb_info *fb, enum sm501_controller head,
fb->var.yres_virtual = fb->var.yres;
} else {
if (info->edid_data) {
ret = fb_find_mode(&fb->var, fb, fb_mode,
ret = fb_find_mode(&fb->var, fb,
info->fb_mode ?: fb_mode,
fb->monspecs.modedb,
fb->monspecs.modedb_len,
&sm501_default_mode, default_bpp);
/* edid_data is no longer needed, free it */
kfree(info->edid_data);
} else {
ret = fb_find_mode(&fb->var, fb,
NULL, NULL, 0, NULL, 8);
@@ -1974,7 +1974,7 @@ static int sm501fb_probe(struct platform_device *pdev)
/* Get EDID */
cp = of_get_property(np, "mode", &len);
if (cp)
strcpy(fb_mode, cp);
info->fb_mode = kstrdup(cp, GFP_KERNEL);
prop = of_get_property(np, "edid", &len);
if (prop && len == EDID_LENGTH) {
info->edid_data = kmemdup(prop, EDID_LENGTH,
@@ -2031,6 +2031,12 @@ static int sm501fb_probe(struct platform_device *pdev)
goto err_started_crt;
}
/* These aren't needed any more */
kfree(info->edid_data);
kfree(info->fb_mode);
info->edid_data = NULL;
info->fb_mode = NULL;
/* we registered, return ok */
return 0;
@@ -2048,6 +2054,8 @@ static int sm501fb_probe(struct platform_device *pdev)
framebuffer_release(info->fb[HEAD_CRT]);
err_alloc:
kfree(info->edid_data);
kfree(info->fb_mode);
kfree(info);
return ret;