find_next bitops on m68k (find_next_zero_bit, find_next_bit, and
ext2_find_next_bit) 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_fist_bit() takes unsigned int as the size argument.
4. find_first_bit will access bitmap[2~] until it find any set bits.
This switches find_next bitops to use generic implementation of
find bitops to fix the problem.
(Please feel free to suggest alternative way to fix)
Signed-off-by: Akinobu Mita <akinobu.mita@xxxxxxxxx>
Cc: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
Cc: Roman Zippel <zippel@xxxxxxxxxxxxxx>
Cc: linux-m68k@xxxxxxxxxxxxxxxxxxxx
Cc: Andreas Schwab <schwab@xxxxxxxxxxxxxx>
Cc: Michael Schmitz <schmitzmic@xxxxxxxxxxxxxx>
---
arch/m68k/Kconfig | 4 +
arch/m68k/include/asm/bitops_mm.h | 188 ++-----------------------------------
2 files changed, 13 insertions(+), 179 deletions(-)
diff --git a/arch/m68k/Kconfig b/arch/m68k/Kconfig
index bc9271b..c11e029 100644
--- a/arch/m68k/Kconfig
+++ b/arch/m68k/Kconfig
@@ -28,6 +28,10 @@ config GENERIC_HWEIGHT
bool
default y
+config GENERIC_FIND_NEXT_BIT
+ bool
+ default y
+
config GENERIC_CALIBRATE_DELAY
bool
default y
diff --git a/arch/m68k/include/asm/bitops_mm.h b/arch/m68k/include/asm/bitops_mm.h
index b4ecdaa..c03f400 100644
--- a/arch/m68k/include/asm/bitops_mm.h
+++ b/arch/m68k/include/asm/bitops_mm.h
@@ -176,100 +176,7 @@ static inline int test_bit(int nr, const unsigned long *vaddr)
return (vaddr[nr >> 5] & (1UL << (nr & 31))) != 0;
}
-static inline int find_first_zero_bit(const unsigned long *vaddr,
- unsigned size)
-{
- const unsigned long *p = vaddr;
- int res = 32;
- unsigned long num;
-
- if (!size)
- return 0;
-
- size = (size + 31) >> 5;
- while (!(num = ~*p++)) {
- if (!--size)
- goto out;
- }
-
- __asm__ __volatile__ ("bfffo %1{#0,#0},%0"
- : "=d" (res) : "d" (num & -num));
- res ^= 31;
-out:
- return ((long)p - (long)vaddr - 4) * 8 + res;
-}
-
-static inline int find_next_zero_bit(const unsigned long *vaddr, int size,
- int offset)
-{
- const unsigned long *p = vaddr + (offset >> 5);
- int bit = offset & 31UL, res;
-
- if (offset >= size)
- return size;
-
- if (bit) {
- unsigned long num = ~*p++ & (~0UL << bit);
- offset -= bit;
-
- /* 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);
- offset += 32;
- }
- /* No zero yet, search remaining full bytes for a zero */
- res = find_first_zero_bit(p, size - ((long)p - (long)vaddr) * 8);
- return offset + res;
-}
-
-static inline int find_first_bit(const unsigned long *vaddr, unsigned size)
-{
- const unsigned long *p = vaddr;
- int res = 32;
- unsigned long num;
-
- if (!size)
- return 0;
-
- size = (size + 31) >> 5;
- while (!(num = *p++)) {
- if (!--size)
- goto out;
- }
-
- __asm__ __volatile__ ("bfffo %1{#0,#0},%0"
- : "=d" (res) : "d" (num & -num));
- res ^= 31;
-out:
- return ((long)p - (long)vaddr - 4) * 8 + res;
-}
-
-static inline int find_next_bit(const unsigned long *vaddr, int size,
- int offset)
-{
- const unsigned long *p = vaddr + (offset >> 5);
- int bit = offset & 31UL, res;
-
- if (offset >= size)
- return size;
-
- if (bit) {
- unsigned long num = *p++ & (~0UL << bit);
- offset -= bit;
-
- /* 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);
- offset += 32;
- }
- /* No one yet, search remaining full bytes for a one */
- res = find_first_bit(p, size - ((long)p - (long)vaddr) * 8);
- return offset + res;
-}
+#include <asm-generic/bitops/find.h>
/*
* ffz = Find First Zero in word. Undefined if no zero exists,
@@ -365,10 +272,18 @@ static inline int minix_test_bit(int nr, const void *vaddr)
#define ext2_set_bit_atomic(lock, nr, addr) test_and_set_bit((nr) ^ 24, (unsigned long *)(addr))
#define ext2_clear_bit(nr, addr) __test_and_clear_bit((nr) ^ 24, (unsigned long *)(addr))
#define ext2_clear_bit_atomic(lock, nr, addr) test_and_clear_bit((nr) ^ 24, (unsigned long *)(addr))
+
+extern unsigned long generic_find_next_zero_le_bit(const unsigned long *addr,
+ unsigned long size, unsigned long offset);
+extern unsigned long generic_find_next_le_bit(const unsigned long *addr,
+ unsigned long size, unsigned long offset);
+
#define ext2_find_next_zero_bit(addr, size, offset) \
generic_find_next_zero_le_bit((unsigned long *)addr, size, offset)
#define ext2_find_next_bit(addr, size, offset) \
generic_find_next_le_bit((unsigned long *)addr, size, offset)
+#define ext2_find_first_zero_bit(addr, size) \
+ ext2_find_next_zero_bit(addr, size, 0)
static inline int ext2_test_bit(int nr, const void *vaddr)
{
@@ -376,91 +291,6 @@ static inline int ext2_test_bit(int nr, const void *vaddr)
return (p[nr >> 3] & (1U << (nr & 7))) != 0;
}
-static inline int ext2_find_first_zero_bit(const void *vaddr, unsigned size)
-{
- const unsigned long *p = vaddr, *addr = vaddr;
- int res;
-
- if (!size)
- return 0;
-
- size = (size >> 5) + ((size & 31) > 0);
- while (*p++ == ~0UL)
- {
- if (--size == 0)
- return (p - addr) << 5;
- }
-
- --p;
- for (res = 0; res < 32; res++)
- if (!ext2_test_bit (res, p))
- break;
- return (p - addr) * 32 + res;
-}
-
-static inline unsigned long generic_find_next_zero_le_bit(const unsigned long *addr,
- unsigned long size, unsigned long offset)
-{
- const unsigned long *p = addr + (offset >> 5);
- int bit = offset & 31UL, res;
-
- if (offset >= size)
- return size;
-
- if (bit) {
- /* Look for zero in first longword */
- for (res = bit; res < 32; res++)
- if (!ext2_test_bit (res, p))
- return (p - addr) * 32 + res;
- p++;
- }
- /* No zero yet, search remaining full bytes for a zero */
- res = ext2_find_first_zero_bit (p, size - 32 * (p - addr));
- return (p - addr) * 32 + res;
-}
-
-static inline int ext2_find_first_bit(const void *vaddr, unsigned size)
-{
- const unsigned long *p = vaddr, *addr = vaddr;
- int res;
-
- if (!size)
- return 0;
-
- size = (size >> 5) + ((size & 31) > 0);
- while (*p++ == 0UL) {
- if (--size == 0)
- return (p - addr) << 5;
- }
-
- --p;
- for (res = 0; res < 32; res++)
- if (ext2_test_bit(res, p))
- break;
- return (p - addr) * 32 + res;
-}
-
-static inline unsigned long generic_find_next_le_bit(const unsigned long *addr,
- unsigned long size, unsigned long offset)
-{
- const unsigned long *p = addr + (offset >> 5);
- int bit = offset & 31UL, res;
-
- if (offset >= size)
- return size;
-
- if (bit) {
- /* Look for one in first longword */
- for (res = bit; res < 32; res++)
- if (ext2_test_bit(res, p))
- return (p - addr) * 32 + res;
- p++;
- }
- /* No set bit yet, search remaining full bytes for a set bit */
- res = ext2_find_first_bit(p, size - 32 * (p - addr));
- return (p - addr) * 32 + res;
-}
-
#endif /* __KERNEL__ */
#endif /* _M68K_BITOPS_H */
--
1.7.4
--
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