From: Andy Shevchenko andriy.shevchenko@linux.intel.com
[ Upstream commit d75b26f880f60ead301e79ba0f4a635c5a60767f ]
The %p4cc specifier in some cases might get an unaligned pointer. Due to this we need to make copy to local variable once to avoid potential crashes on some architectures due to improper access.
Fixes: af612e43de6d ("lib/vsprintf: Add support for printing V4L2 and DRM fourccs") Cc: Sakari Ailus sakari.ailus@linux.intel.com Signed-off-by: Andy Shevchenko andriy.shevchenko@linux.intel.com Reviewed-by: Petr Mladek pmladek@suse.com Signed-off-by: Petr Mladek pmladek@suse.com Link: https://lore.kernel.org/r/20220127181233.72910-1-andriy.shevchenko@linux.int... Signed-off-by: Sasha Levin sashal@kernel.org --- lib/vsprintf.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/lib/vsprintf.c b/lib/vsprintf.c index 58d5e567f836..01e61c85f274 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -49,6 +49,7 @@
#include <asm/page.h> /* for PAGE_SIZE */ #include <asm/byteorder.h> /* cpu_to_le16 */ +#include <asm/unaligned.h>
#include <linux/string_helpers.h> #include "kstrtox.h" @@ -1771,7 +1772,7 @@ char *fourcc_string(char *buf, char *end, const u32 *fourcc, char output[sizeof("0123 little-endian (0x01234567)")]; char *p = output; unsigned int i; - u32 val; + u32 orig, val;
if (fmt[1] != 'c' || fmt[2] != 'c') return error_string(buf, end, "(%p4?)", spec); @@ -1779,21 +1780,22 @@ char *fourcc_string(char *buf, char *end, const u32 *fourcc, if (check_pointer(&buf, end, fourcc, spec)) return buf;
- val = *fourcc & ~BIT(31); + orig = get_unaligned(fourcc); + val = orig & ~BIT(31);
- for (i = 0; i < sizeof(*fourcc); i++) { + for (i = 0; i < sizeof(u32); i++) { unsigned char c = val >> (i * 8);
/* Print non-control ASCII characters as-is, dot otherwise */ *p++ = isascii(c) && isprint(c) ? c : '.'; }
- strcpy(p, *fourcc & BIT(31) ? " big-endian" : " little-endian"); + strcpy(p, orig & BIT(31) ? " big-endian" : " little-endian"); p += strlen(p);
*p++ = ' '; *p++ = '('; - p = special_hex_number(p, output + sizeof(output) - 2, *fourcc, sizeof(u32)); + p = special_hex_number(p, output + sizeof(output) - 2, orig, sizeof(u32)); *p++ = ')'; *p = '\0';