pstore: ram_core: fix possible overflow in persistent_ram_init_ecc()

[ Upstream commit 86222a8fc16ec517de8da2604d904c9df3a08e5d ]

In persistent_ram_init_ecc(), on 64-bit arches DIV_ROUND_UP() will return
64-bit value since persistent_ram_zone::buffer_size has type size_t which
is derived from the 64-bit *unsigned long*, while the ecc_blocks variable
this value gets assigned to has (always 32-bit) *int* type.  Even if that
value fits into *int* type, an overflow is still possible when calculating
the size_t typed ecc_total variable further below since there's no cast to
any 64-bit type before multiplication.  Declaring the ecc_blocks variable
as *size_t* should fix this mess...

Found by Linux Verification Center (linuxtesting.org) with the SVACE static
analysis tool.

Fixes: 9cc05ad97c57 ("staging: android: persistent_ram: refactor ecc support")
Signed-off-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Link: https://lore.kernel.org/r/20231105202936.25694-1-s.shtylyov@omp.ru
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/fs/pstore/ram_core.c b/fs/pstore/ram_core.c
index 650e437..f1848cd 100644 (file)
--- a/fs/pstore/ram_core.c
+++ b/fs/pstore/ram_core.c
@@ -190,7 +190,7 @@ static int persistent_ram_init_ecc(struct persistent_ram_zone *prz,
 {
        int numerr;
        struct persistent_ram_buffer *buffer = prz->buffer;
-       int ecc_blocks;
+       size_t ecc_blocks;
        size_t ecc_total;
 
        if (!ecc_info || !ecc_info->ecc_size)