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video: fbdev: via: refactor strcpy and viafb_name

PATCH Superseded Ajith P V 2 participants 2 messages Aug 14

Subsystems (2)
Framebuffer layer Via unichrome(pro)/CHROME9 framebuffer driver

v2 of 4 Superseded Latest is v4 →

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Ajith P V

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PATCH v2 1/1 video: fbdev: via: refactor strcpy and viafb_name

Replace the deprecated and unbounded strcpy() function with the safer strscpy() alternative when setting up the framebuffer fixed screen information [1][2].

It aligns this driver with the ongoing kernel-wide security initiative to eliminate unbounded string copies, hardening the code against future modifications.

Additionally, convert the file-scope viafb_name pointer into a static const char[] array and update its value to "viafb". This permits the compiler to execute compile-time bounds checking and aggressively optimize the runtime string copy operation out entirely.

This is a proactive API cleanup and there is no functional performance or truncation risk.

Link https://www.kernel.org/doc/html/latest/process/deprecated.html#strcpy [1]
Link https://github.com/KSPP/linux/issues/88 [2]
Signed-off-by Ajith P V <[email protected]>

---
v2:
- Keep variable static but change it to a const array
'static const char viafb_name[] = "viafb"' as suggested by Helge Deller to let the compiler leverage compile-time checks.

 drivers/video/fbdev/via/viafbdev.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
drivers/video/fbdev/via/viafbdev.c +2 -2
index 80f95dac32c8..b3a2e07b61a7 100644
@@ -16,7 +16,7 @@
 #define _MASTER_FILE
 #include "global.h"
 
-static char *viafb_name = "Via";
+static const char viafb_name[] = "viafb";
 static u32 pseudo_pal[17];
 
 /* video mode */

@@ -144,7 +144,7 @@ static void viafb_setup_fixinfo(struct fb_fix_screeninfo *fix,
 	struct viafb_par *viaparinfo)
 {
 	memset(fix, 0, sizeof(struct fb_fix_screeninfo));
-	strcpy(fix->id, viafb_name);
+	strscpy(fix->id, viafb_name, sizeof(fix->id));
 
 	fix->smem_start = viaparinfo->fbmem;
 	fix->smem_len = viaparinfo->fbmem_free;
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2.43.0
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Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider: - [Critical] Changing the driver identification string exposed in the fb_fix_screeninfo structure from…

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Critical] Changing the driver identification string exposed in the fb_fix_screeninfo structure from "Via" to "viafb" breaks userspace ABI backward compatibility. --

--- Patch [1]: [PATCH v2] video: fbdev: via: refactor strcpy and viafb_name --- commit 31193988a75e693bb97d9723171d248ff11a2f17
Author: Ajith P V <[email protected]>

video: fbdev: via: refactor strcpy and viafb_name

This commit replaces unbounded strcpy() calls with strscpy() to harden the framebuffer screen info initialization. It also converts the viafb_name pointer into a static const char array and changes its string value.

Link https://www.kernel.org/doc/html/latest/process/deprecated.html#strcpy [1]
Link https://github.com/KSPP/linux/issues/88 [2]

drivers/video/fbdev/via/viafbdev.c line 19

Quoted 10 lines
drivers/video/fbdev/via/viafbdev.c +1 -1
index 80f95dac32c8c..b3a2e07b61a7c 100644
@@ -16,7 +16,7 @@
 #define _MASTER_FILE
 #include "global.h"
 
-static char *viafb_name = "Via";
+static const char viafb_name[] = "viafb";

[Severity: Critical]
Does changing this string from "Via" to "viafb" cause a userspace ABI regression?

Userspace tools and display servers, such as Xorg's via driver, often rely on the exact identification string returned in the id field of fb_fix_screeninfo by the framebuffer ioctl to detect hardware and apply specific quirks.

Could the compile-time bounds checking and optimization benefits still be achieved without modifying the exposed string value, perhaps by defining it as 'static const char viafb_name[] = "Via";' instead?

Quoted 3 lines
drivers/video/fbdev/via/viafbdev.c +0 -0
 static u32 pseudo_pal[17];
 
 /* video mode */

[ ... ]

Quoted 9 lines
drivers/video/fbdev/via/viafbdev.c +1 -1
@@ -144,7 +144,7 @@ static void viafb_setup_fixinfo(struct fb_fix_screeninfo *fix,
 	struct viafb_par *viaparinfo)
 {
 	memset(fix, 0, sizeof(struct fb_fix_screeninfo));
-	strcpy(fix->id, viafb_name);
+	strscpy(fix->id, viafb_name, sizeof(fix->id));
 
 	fix->smem_start = viaparinfo->fbmem;
 	fix->smem_len = viaparinfo->fbmem_free;
Signature · 1 line
Sashiko AI review · https://sashiko.dev/#/patchset/[email protected]?part=1