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[2603:9001:3d00:5353::14c1]) by smtp.gmail.com with ESMTPSA id 46e09a7af769-7189cc59b45sm1980847a34.6.2024.11.04.07.24.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 04 Nov 2024 07:24:22 -0800 (PST) From: Jennifer Berringer To: Srinivas Kandagatla , Sebastian Reichel , Greg Kroah-Hartman , Maxime Ripard Cc: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, Jennifer Berringer Subject: [PATCH v3 1/3] nvmem: core: improve range check for nvmem_cell_write() Date: Mon, 4 Nov 2024 10:23:10 -0500 Message-ID: <20241104152312.3813601-2-jberring@redhat.com> X-Mailer: git-send-email 2.46.2 In-Reply-To: <20241104152312.3813601-1-jberring@redhat.com> References: <20241104152312.3813601-1-jberring@redhat.com> Precedence: bulk X-Mailing-List: linux-pm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 When __nvmem_cell_entry_write() is called for an nvmem cell that does not need bit shifting, it requires that the len parameter exactly matches the nvmem cell size. However, when the nvmem cell has a nonzero bit_offset, it was skipping this check. Accepting values of len larger than the cell size results in nvmem_cell_prepare_write_buffer() trying to write past the end of a heap buffer that it allocates. Add a check to avoid that problem and instead return -EINVAL when len doesn't match the number of bits expected by the nvmem cell when bit_offset is nonzero. This check uses cell->nbits in order to allow providing the smaller size to cells that are shifted into another byte by bit_offset. For example, a cell with nbits=8 and nonzero bit_offset would have bytes=2 but should accept a 1-byte write here, although no current callers depend on this. Fixes: 69aba7948cbe ("nvmem: Add a simple NVMEM framework for consumers") Signed-off-by: Jennifer Berringer --- drivers/nvmem/core.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c index 33ffa2aa4c11..4a5a6efe4bab 100644 --- a/drivers/nvmem/core.c +++ b/drivers/nvmem/core.c @@ -1780,6 +1780,8 @@ static int __nvmem_cell_entry_write(struct nvmem_cell_entry *cell, void *buf, si return -EINVAL; if (cell->bit_offset || cell->nbits) { + if (len != BITS_TO_BYTES(cell->nbits) && len != cell->bytes) + return -EINVAL; buf = nvmem_cell_prepare_write_buffer(cell, buf, len); if (IS_ERR(buf)) return PTR_ERR(buf);