[PATCH] nvmem: core: Fix possible buffer overflow on nvmem cell write

From: Loic Poulain
Date: Tue Oct 03 2023 - 09:13:52 EST


Nothing prevents a nvmem consumer to try writing excessive data to a
given nvmem cell (except when bit_offset is 0). The allocated buffer
of size 'cell->bytes' in nvmem_cell_prepare_write_buffer may not be
large enough to host the copied 'len' bytes.

Signed-off-by: Loic Poulain <loic.poulain@xxxxxxxxxx>
---
drivers/nvmem/core.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index eaf6a3fe8ca6..0b27ab3b3b86 100644
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -1654,6 +1654,9 @@ static void *nvmem_cell_prepare_write_buffer(struct nvmem_cell_entry *cell,
int i, rc, nbits, bit_offset = cell->bit_offset;
u8 v, *p, *buf, *b, pbyte, pbits;

+ if (len > cell->bytes)
+ return ERR_PTR(-EINVAL);
+
nbits = cell->nbits;
buf = kzalloc(cell->bytes, GFP_KERNEL);
if (!buf)
--
2.34.1