From: Liu ShuoX <[email protected]> commit 017321cf390045dd4c4afc4a232995ea50bcf66d upstream.
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 <[email protected]> Acked-by: Kees Cook <[email protected]> Signed-off-by: Tony Luck <[email protected]> Signed-off-by: Willy Tarreau <[email protected]> --- fs/pstore/ram_core.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/pstore/ram_core.c b/fs/pstore/ram_core.c index bda61a7..0b367ef 100644 --- a/fs/pstore/ram_core.c +++ b/fs/pstore/ram_core.c @@ -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); -- 2.8.0.rc2.1.gbe9624a
