[tip: objtool/urgent] objtool, spi: amd: Fix out-of-bounds stack access in amd_set_spi_freq()

[tip-bot2 for Josh Poimboeuf]

The following commit has been merged into the objtool/urgent branch of tip:

Commit-ID:     76e51db43fe4aaaebcc5ddda67b0807f7c9bdecc
Gitweb:        https://git.kernel.org/tip/76e51db43fe4aaaebcc5ddda67b0807f7c9bdecc
Author:        Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
AuthorDate:    Mon, 24 Mar 2025 14:56:04 -07:00
Committer:     Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Tue, 25 Mar 2025 23:00:03 +01:00

objtool, spi: amd: Fix out-of-bounds stack access in amd_set_spi_freq()

If speed_hz < AMD_SPI_MIN_HZ, amd_set_spi_freq() iterates over the
entire amd_spi_freq array without breaking out early, causing 'i' to go
beyond the array bounds.

Fix that by stopping the loop when it gets to the last entry, so the low
speed_hz value gets clamped up to AMD_SPI_MIN_HZ.

Fixes the following warning with an UBSAN kernel:

  drivers/spi/spi-amd.o: error: objtool: amd_set_spi_freq() falls through to next function amd_spi_set_opcode()

Fixes: 3fe26121dc3a ("spi: amd: Configure device speed")
Reported-by: kernel test robot <lkp@xxxxxxxxx>
Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Acked-by: Mark Brown <broonie@xxxxxxxxxx>
Cc: Raju Rangoju <Raju.Rangoju@xxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/78fef0f2434f35be9095bcc9ffa23dd8cab667b9.1742852847.git.jpoimboe@xxxxxxxxxx
Closes: https://lore.kernel.org/r/202503161828.RUk9EhWx-lkp@xxxxxxxxx/
---
 drivers/spi/spi-amd.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/spi/spi-amd.c b/drivers/spi/spi-amd.c
index c859974..17fc0b1 100644
--- a/drivers/spi/spi-amd.c
+++ b/drivers/spi/spi-amd.c
@@ -302,7 +302,7 @@ static void amd_set_spi_freq(struct amd_spi *amd_spi, u32 speed_hz)
 {
 	unsigned int i, spd7_val, alt_spd;
 
-	for (i = 0; i < ARRAY_SIZE(amd_spi_freq); i++)
+	for (i = 0; i < ARRAY_SIZE(amd_spi_freq)-1; i++)
 		if (speed_hz >= amd_spi_freq[i].speed_hz)
 			break;