[PATCH 1/4] lib/vsprintf.c: Consume 'p' in format_decode

[PATCH 1/4] lib/vsprintf.c: Consume 'p' in format_decode

[Rasmus Villemoes]

It seems a little simpler to consume the p from a %p specifier in
format_decode, just as it is done for the surrounding %c, %s and %%
cases.

While there, delete a redundant and misplaced comment.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
---
 lib/vsprintf.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index ec337f64f52d..98ad170b10e0 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -1604,8 +1604,7 @@ qualifier:
 
 	case 'p':
 		spec->type = FORMAT_TYPE_PTR;
-		return fmt - start;
-		/* skip alnum */
+		return ++fmt - start;
 
 	case '%':
 		spec->type = FORMAT_TYPE_PERCENT_CHAR;
@@ -1794,7 +1793,7 @@ int vsnprintf(char *buf, size_t size, const char *fmt, va_list args)
 			break;
 
 		case FORMAT_TYPE_PTR:
-			str = pointer(fmt+1, str, end, va_arg(args, void *),
+			str = pointer(fmt, str, end, va_arg(args, void *),
 				      spec);
 			while (isalnum(*fmt))
 				fmt++;
@@ -2232,7 +2231,7 @@ int bstr_printf(char *buf, size_t size, const char *fmt, const u32 *bin_buf)
 		}
 
 		case FORMAT_TYPE_PTR:
-			str = pointer(fmt+1, str, end, get_arg(void *), spec);
+			str = pointer(fmt, str, end, get_arg(void *), spec);
 			while (isalnum(*fmt))
 				fmt++;
 			break;
-- 
2.1.3

[PATCH 2/4] lib/vsprintf.c: Improve sanity check in vsnprintf()

[Rasmus Villemoes]

On 64 bit, size may very well be huge even if bit 31 happens to be
0. Somehow it doesn't feel right that one can pass a 5 GiB buffer but
not a 3 GiB one. So cap at INT_MAX as was probably the intention all
along. This is also the made-up value passed by sprintf and vsprintf.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
---
 lib/vsprintf.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 98ad170b10e0..cf12ba86205c 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -1727,7 +1727,7 @@ int vsnprintf(char *buf, size_t size, const char *fmt, va_list args)
 
 	/* Reject out-of-range values early.  Large positive sizes are
 	   used for unknown buffer sizes. */
-	if (WARN_ON_ONCE((int) size < 0))
+	if (WARN_ON_ONCE(size > INT_MAX))
 		return 0;
 
 	str = buf;
-- 
2.1.3

[PATCH 3/4] lib/vsprintf.c: Don't try to fix pointer wrap-around

[Rasmus Villemoes]

Actual kernel buffers can't wrap into the user address space. If
someone manages to pass a buf/size combination that wraps, it is most
likely due to a bug in the caller. Instead of trying to fix it by
using a smaller part of the buffer, bail out.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
---
 lib/vsprintf.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index cf12ba86205c..1ec6a78f169b 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -1733,11 +1733,9 @@ int vsnprintf(char *buf, size_t size, const char *fmt, va_list args)
 	str = buf;
 	end = buf + size;
 
-	/* Make sure end is always >= buf */
-	if (end < buf) {
-		end = ((void *)-1);
-		size = end - buf;
-	}
+	/* Also bail out if buf+size wraps */
+	if (WARN_ON_ONCE(end < buf))
+		return 0;
 
 	while (*fmt) {
 		const char *old_fmt = fmt;
-- 
2.1.3

[PATCH 4/4] lib/vsprintf.c: Replace while with do-while in skip_atoi

[Rasmus Villemoes]

All callers of skip_atoi have already checked for the first character
being a digit. In this case, gcc generates simpler code for a do
while-loop.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
---
 lib/vsprintf.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 1ec6a78f169b..e152da53cbd2 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -114,8 +114,9 @@ int skip_atoi(const char **s)
 {
 	int i = 0;
 
-	while (isdigit(**s))
+	do {
 		i = i*10 + *((*s)++) - '0';
+	} while (isdigit(**s));
 
 	return i;
 }
-- 
2.1.3