diff options
| author | Michal Nazarewicz <mina86@mina86.com> | 2013-11-12 15:11:42 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-11-13 12:09:35 +0900 |
| commit | bb67093796a41e0f2601f5c0022fd8873ed59fee (patch) | |
| tree | f52f201e90f5b6678a83bf19a399bec238f906de /drivers/w1/w1.c | |
| parent | 75f9e937d24fdf661ebd5c9bed05caa4aad90539 (diff) | |
drivers: w1: make w1_slave::flags long to avoid memory corruption
On architectures where long is more then 32 bits, modifying a 32-bit field
with set_bit (and other atomic bit operations) may cause bytes following
the field to by modified.
Because the endianness of the bits within a field is the native endianness
of the CPU[1], on big-endian machines, bit number zero is in the last byte
of the field.
Therefore, `set_bit(0, ptr)' on a 64-bit big-endian machine is roughly
equivalent to `((char *)ptr)[7] |= 1', and since w1 driver uses a 32-bit
field for holding the flags, this causes bytes beyond the field to be
modified.
[1] From Documentation/atomic_ops.txt:
Native atomic bit operations are defined to operate on objects
aligned to the size of an "unsigned long" C data type, and are
least of that size. The endianness of the bits within each
"unsigned long" are the native endianness of the cpu.
Signed-off-by: Michal Nazarewicz <mina86@mina86.com>
Cc: Evgeniy Polyakov <zbr@ioremap.net>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/w1/w1.c')
| -rw-r--r-- | drivers/w1/w1.c | 10 |
1 files changed, 5 insertions, 5 deletions
diff --git a/drivers/w1/w1.c b/drivers/w1/w1.c index fa932c2f7d9..66efa96c460 100644 --- a/drivers/w1/w1.c +++ b/drivers/w1/w1.c @@ -709,7 +709,7 @@ static int w1_attach_slave_device(struct w1_master *dev, struct w1_reg_num *rn) sl->owner = THIS_MODULE; sl->master = dev; - set_bit(W1_SLAVE_ACTIVE, (long *)&sl->flags); + set_bit(W1_SLAVE_ACTIVE, &sl->flags); memset(&msg, 0, sizeof(msg)); memcpy(&sl->reg_num, rn, sizeof(sl->reg_num)); @@ -866,7 +866,7 @@ void w1_slave_found(struct w1_master *dev, u64 rn) sl = w1_slave_search_device(dev, tmp); if (sl) { - set_bit(W1_SLAVE_ACTIVE, (long *)&sl->flags); + set_bit(W1_SLAVE_ACTIVE, &sl->flags); } else { if (rn && tmp->crc == w1_calc_crc8((u8 *)&rn_le, 7)) w1_attach_slave_device(dev, tmp); @@ -984,14 +984,14 @@ void w1_search_process_cb(struct w1_master *dev, u8 search_type, struct w1_slave *sl, *sln; list_for_each_entry(sl, &dev->slist, w1_slave_entry) - clear_bit(W1_SLAVE_ACTIVE, (long *)&sl->flags); + clear_bit(W1_SLAVE_ACTIVE, &sl->flags); w1_search_devices(dev, search_type, cb); list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) { - if (!test_bit(W1_SLAVE_ACTIVE, (unsigned long *)&sl->flags) && !--sl->ttl) + if (!test_bit(W1_SLAVE_ACTIVE, &sl->flags) && !--sl->ttl) w1_slave_detach(sl); - else if (test_bit(W1_SLAVE_ACTIVE, (unsigned long *)&sl->flags)) + else if (test_bit(W1_SLAVE_ACTIVE, &sl->flags)) sl->ttl = dev->slave_ttl; } |