From ff1279e42d011c054b565312a5b938613b3a83c0 Mon Sep 17 00:00:00 2001 From: Liu ShuoX Date: Wed, 12 Mar 2014 21:24:44 +0800 Subject: [PATCH] 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: Liu ShuoX Acked-by: Kees Cook Signed-off-by: Tony Luck Signed-off-by: Pranav Vashi --- 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 2a40e66de26..1c934adcba3 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);