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Commit 017321cf authored by Liu ShuoX's avatar Liu ShuoX Committed by Tony Luck
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pstore: Fix buffer overflow while write offset equal to buffer size 



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: default avatarLiu ShuoX <shuox.liu@intel.com>
Acked-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatarTony Luck <tony.luck@intel.com>
parent 34f0ec82

fs/pstore/ram_core.c

+2 −2
Original line number Diff line number Diff line
@@ -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);