From f82a519f1262963d6ab30fa238721463fad2e0c8 Mon Sep 17 00:00:00 2001 From: Geert Uytterhoeven Date: Sun, 3 Apr 2011 14:00:10 +0200 Subject: [PATCH] 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 Cc: Andreas Schwab Signed-off-by: Geert Uytterhoeven --- arch/m68k/include/asm/bitops_mm.h | 81 +++++++++++++++++++++---------- 1 file changed, 55 insertions(+), 26 deletions(-) diff --git a/arch/m68k/include/asm/bitops_mm.h b/arch/m68k/include/asm/bitops_mm.h index 5bd3afadeafa..e9020f88a748 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); -- 2.20.1