[PATCH] mtd: spi-nor: Check for spi_nor_hwcaps_read2cmd() return value

[Richard Weinberger]

The function can return a negativ value in case of errors,
don't use it blindly as array index.

Detected by CoverityScan CID#1418067 ("Memory - illegal accesses")
Fixes: f384b352cbf0 ("mtd: spi-nor: parse Serial Flash Discoverable
Parameters (SFDP) tables")
Signed-off-by: Richard Weinberger <richard at nod.at>
---
 drivers/mtd/spi-nor/spi-nor.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
index cf1d4a15e10a..d71765739a93 100644
--- a/drivers/mtd/spi-nor/spi-nor.c
+++ b/drivers/mtd/spi-nor/spi-nor.c
@@ -2145,6 +2145,9 @@ static int spi_nor_parse_bfpt(struct spi_nor *nor,
 
 		params->hwcaps.mask |= rd->hwcaps;
 		cmd = spi_nor_hwcaps_read2cmd(rd->hwcaps);
+		if (cmd < 0)
+			return -EINVAL;
+
 		read = &params->reads[cmd];
 		half = bfpt.dwords[rd->settings_dword] >> rd->settings_shift;
 		spi_nor_set_read_settings_from_bfpt(read, half, rd->proto);
-- 
2.13.5