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authorGeert Uytterhoeven <geert@linux-m68k.org>2011-04-03 14:00:10 +0200
committerGeert Uytterhoeven <geert@linux-m68k.org>2011-05-19 18:19:09 +0200
commitf82a519f1262963d6ab30fa238721463fad2e0c8 (patch)
treec7808cc9a265b923a20d96d5a9aff2c2f1669d4a /arch/m68k
parent359c47ea71be21c1105ae474e8c90ec3e988bbdf (diff)
m68k: bitops - Never step beyond the end of the bitmap
find_next bitops on m68k (find_next_zero_bit, find_next_bit, and find_next_bit_le) may cause out of bounds memory access when the bitmap size in bits % 32 != 0 and offset (the bitnumber to start searching at) is very close to the bitmap size. For example, unsigned long bitmap[2] = { 0, 0 }; find_next_bit(bitmap, 63, 62); 1. find_next_bit() tries to find any set bits in bitmap[1], but no bits set. 2. Then find_first_bit(bimap + 2, -1) 3. Unfortunately find_first_bit() takes unsigned int as the size argument. 4. find_first_bit will access bitmap[2~] until it find any set bits. Add missing tests for stepping beyond the end of the bitmap to all find_{first,next}_*() functions, and make sure they never return a value larger than the bitmap size. Reported-by: Akinobu Mita <akinobu.mita@gmail.com> Cc: Andreas Schwab <schwab@linux-m68k.org> Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Diffstat (limited to 'arch/m68k')
-rw-r--r--arch/m68k/include/asm/bitops_mm.h81
1 files changed, 55 insertions, 26 deletions
diff --git a/arch/m68k/include/asm/bitops_mm.h b/arch/m68k/include/asm/bitops_mm.h
index 5bd3afadeaf..e9020f88a74 100644
--- a/arch/m68k/include/asm/bitops_mm.h
+++ b/arch/m68k/include/asm/bitops_mm.h
@@ -181,14 +181,15 @@ static inline int find_first_zero_bit(const unsigned long *vaddr,
{
const unsigned long *p = vaddr;
int res = 32;
+ unsigned int words;
unsigned long num;
if (!size)
return 0;
- size = (size + 31) >> 5;
+ words = (size + 31) >> 5;
while (!(num = ~*p++)) {
- if (!--size)
+ if (!--words)
goto out;
}
@@ -196,7 +197,8 @@ static inline int find_first_zero_bit(const unsigned long *vaddr,
: "=d" (res) : "d" (num & -num));
res ^= 31;
out:
- return ((long)p - (long)vaddr - 4) * 8 + res;
+ res += ((long)p - (long)vaddr - 4) * 8;
+ return res < size ? res : size;
}
static inline int find_next_zero_bit(const unsigned long *vaddr, int size,
@@ -215,9 +217,14 @@ static inline int find_next_zero_bit(const unsigned long *vaddr, int size,
/* Look for zero in first longword */
__asm__ __volatile__ ("bfffo %1{#0,#0},%0"
: "=d" (res) : "d" (num & -num));
- if (res < 32)
- return offset + (res ^ 31);
+ if (res < 32) {
+ offset += res ^ 31;
+ return offset < size ? offset : size;
+ }
offset += 32;
+
+ if (offset >= size)
+ return size;
}
/* No zero yet, search remaining full bytes for a zero */
return offset + find_first_zero_bit(p, size - offset);
@@ -227,14 +234,15 @@ static inline int find_first_bit(const unsigned long *vaddr, unsigned size)
{
const unsigned long *p = vaddr;
int res = 32;
+ unsigned int words;
unsigned long num;
if (!size)
return 0;
- size = (size + 31) >> 5;
+ words = (size + 31) >> 5;
while (!(num = *p++)) {
- if (!--size)
+ if (!--words)
goto out;
}
@@ -242,7 +250,8 @@ static inline int find_first_bit(const unsigned long *vaddr, unsigned size)
: "=d" (res) : "d" (num & -num));
res ^= 31;
out:
- return ((long)p - (long)vaddr - 4) * 8 + res;
+ res += ((long)p - (long)vaddr - 4) * 8;
+ return res < size ? res : size;
}
static inline int find_next_bit(const unsigned long *vaddr, int size,
@@ -261,9 +270,14 @@ static inline int find_next_bit(const unsigned long *vaddr, int size,
/* Look for one in first longword */
__asm__ __volatile__ ("bfffo %1{#0,#0},%0"
: "=d" (res) : "d" (num & -num));
- if (res < 32)
- return offset + (res ^ 31);
+ if (res < 32) {
+ offset += res ^ 31;
+ return offset < size ? offset : size;
+ }
offset += 32;
+
+ if (offset >= size)
+ return size;
}
/* No one yet, search remaining full bytes for a one */
return offset + find_first_bit(p, size - offset);
@@ -364,23 +378,25 @@ static inline int test_bit_le(int nr, const void *vaddr)
static inline int find_first_zero_bit_le(const void *vaddr, unsigned size)
{
const unsigned long *p = vaddr, *addr = vaddr;
- int res;
+ int res = 0;
+ unsigned int words;
if (!size)
return 0;
- size = (size >> 5) + ((size & 31) > 0);
- while (*p++ == ~0UL)
- {
- if (--size == 0)
- return (p - addr) << 5;
+ words = (size >> 5) + ((size & 31) > 0);
+ while (*p++ == ~0UL) {
+ if (--words == 0)
+ goto out;
}
--p;
for (res = 0; res < 32; res++)
if (!test_bit_le(res, p))
break;
- return (p - addr) * 32 + res;
+out:
+ res += (p - addr) * 32;
+ return res < size ? res : size;
}
static inline unsigned long find_next_zero_bit_le(const void *addr,
@@ -398,10 +414,15 @@ static inline unsigned long find_next_zero_bit_le(const void *addr,
offset -= bit;
/* Look for zero in first longword */
for (res = bit; res < 32; res++)
- if (!test_bit_le(res, p))
- return offset + res;
+ if (!test_bit_le(res, p)) {
+ offset += res;
+ return offset < size ? offset : size;
+ }
p++;
offset += 32;
+
+ if (offset >= size)
+ return size;
}
/* No zero yet, search remaining full bytes for a zero */
return offset + find_first_zero_bit_le(p, size - offset);
@@ -410,22 +431,25 @@ static inline unsigned long find_next_zero_bit_le(const void *addr,
static inline int find_first_bit_le(const void *vaddr, unsigned size)
{
const unsigned long *p = vaddr, *addr = vaddr;
- int res;
+ int res = 0;
+ unsigned int words;
if (!size)
return 0;
- size = (size >> 5) + ((size & 31) > 0);
+ words = (size >> 5) + ((size & 31) > 0);
while (*p++ == 0UL) {
- if (--size == 0)
- return (p - addr) << 5;
+ if (--words == 0)
+ goto out;
}
--p;
for (res = 0; res < 32; res++)
if (test_bit_le(res, p))
break;
- return (p - addr) * 32 + res;
+out:
+ res += (p - addr) * 32;
+ return res < size ? res : size;
}
static inline unsigned long find_next_bit_le(const void *addr,
@@ -443,10 +467,15 @@ static inline unsigned long find_next_bit_le(const void *addr,
offset -= bit;
/* Look for one in first longword */
for (res = bit; res < 32; res++)
- if (test_bit_le(res, p))
- return offset + res;
+ if (test_bit_le(res, p)) {
+ offset += res;
+ return offset < size ? offset : size;
+ }
p++;
offset += 32;
+
+ if (offset >= size)
+ return size;
}
/* No set bit yet, search remaining full bytes for a set bit */
return offset + find_first_bit_le(p, size - offset);