From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?UTF-8?q?Marek=20Beh=C3=BAn?= Date: Sun, 7 Mar 2021 05:25:02 +0100 Subject: [PATCH u-boot-dm 03/39] regmap: fix a serious pointer casting bug In-Reply-To: <20210307042538.21229-1-marek.behun@nic.cz> References: <20210307042538.21229-1-marek.behun@nic.cz> Message-ID: <20210307042538.21229-4-marek.behun@nic.cz> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de There is a serious bug in regmap_read() and regmap_write() functions where an uint pointer is cast to (void *) which is then cast to (u8 *), (u16 *), (u32 *) or (u64 *), depending on register width of the map. For example given a regmap with 16-bit register width the code int val = 0x12340000; regmap_read(map, 0, &val); only changes the lower 16 bits of val on little-endian machines. The upper 16 bits will remain 0x1234. Nobody noticed this probably because this bug can be triggered with regmap_write() only on big-endian architectures (which are not used by many people anymore), and on little endian this bug has consequences only if register width is 8 or 16 bits and also the memory place to which regmap_read() should store it's result has non-zero upper bits, which it seems doesn't happen anywhere in U-Boot normally. CI managed to trigger this bug in unit test of dm_test_devm_regmap_field when compiled for sandbox_defconfig using LTO. Fix this simply by taking into account that regmap_raw_read() and regmap_raw_write() behave as if the data given to these functions were in little-endian format, i.e. use cpu_to_le32() / le32_to_cpu(). In regmap_read() also zero out the space so that we don't get invalid result if regmap_raw_read() does not fill the whole object. Signed-off-by: Marek Beh?n Reviewed-by: Simon Glass Reviewed-by: Heiko Schocher --- drivers/core/regmap.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/drivers/core/regmap.c b/drivers/core/regmap.c index b51ce108c1..5d37006fff 100644 --- a/drivers/core/regmap.c +++ b/drivers/core/regmap.c @@ -435,7 +435,16 @@ int regmap_raw_read(struct regmap *map, uint offset, void *valp, size_t val_len) int regmap_read(struct regmap *map, uint offset, uint *valp) { - return regmap_raw_read(map, offset, valp, map->width); + int res; + + *valp = 0; + res = regmap_raw_read(map, offset, valp, map->width); + if (res) + return res; + + *valp = le32_to_cpu(*valp); + + return 0; } static inline void __write_8(u8 *addr, const u8 *val, @@ -546,6 +555,8 @@ int regmap_raw_write(struct regmap *map, uint offset, const void *val, int regmap_write(struct regmap *map, uint offset, uint val) { + val = cpu_to_le32(val); + return regmap_raw_write(map, offset, &val, map->width); } -- 2.26.2