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pstore: Fix buffer overflow while write offset equal to buffer size

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In case new offset is equal to prz->buffer_size, it won't wrap at this
time and will return old(overflow) value next time.

Signed-off-by: Liu ShuoX <shuox.liu@intel.com>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>
This commit is contained in:
Liu ShuoX 2014-03-12 21:24:44 +08:00 committed by Tony Luck
parent 34f0ec82e0
commit 017321cf39
1 changed files with 2 additions and 2 deletions
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4
fs/pstore/ram_core.c
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@ -54,7 +54,7 @@ static size_t buffer_start_add_atomic(struct persistent_ram_zone *prz, size_t a)
do {
old = atomic_read(&prz->buffer->start);
new = old + a;
while (unlikely(new > prz->buffer_size))
while (unlikely(new >= prz->buffer_size))
new -= prz->buffer_size;
} while (atomic_cmpxchg(&prz->buffer->start, old, new) != old);
@ -91,7 +91,7 @@ static size_t buffer_start_add_locked(struct persistent_ram_zone *prz, size_t a)
old = atomic_read(&prz->buffer->start);
new = old + a;
while (unlikely(new > prz->buffer_size))
while (unlikely(new >= prz->buffer_size))
new -= prz->buffer_size;
atomic_set(&prz->buffer->start, new);