Messages in this thread Patch in this message | | | From | Andy Shevchenko <> | Subject | [PATCH v4 1/2] vsprintf: Fix potential unaligned access | Date | Thu, 27 Jan 2022 20:12:32 +0200 |
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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> --- v4: no changes lib/vsprintf.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/lib/vsprintf.c b/lib/vsprintf.c index 61528094ec87..4e8f3e9acb99 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" @@ -1762,7 +1763,7 @@ 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); @@ -1770,21 +1771,22 @@ 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'; -- 2.34.1
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