mtd: spi-nor: Fix shift-out-of-bounds in spi_nor_set_erase_type

spi_nor_set_erase_type() was used either to set or to mask out an erase
type. When we used it to mask out an erase type a shift-out-of-bounds
was hit:
UBSAN: shift-out-of-bounds in drivers/mtd/spi-nor/core.c:2237:24
shift exponent 4294967295 is too large for 32-bit type 'int'

The setting of the size_{shift, mask} and of the opcode are unnecessary
when the erase size is zero, as throughout the code just the erase size
is considered to determine whether an erase type is supported or not.
Setting the opcode to 0xFF was wrong too as nobody guarantees that 0xFF
is an unused opcode. Thus when masking out an erase type, just set the
erase size to zero. This will fix the shift-out-of-bounds.

Fixes: 5390a8d ("mtd: spi-nor: add support to non-uniform SFDP SPI NOR flash memories")
Cc: [email protected]
Reported-by: Alexander Stein <[email protected]>
Signed-off-by: Louis Rannou <[email protected]>
Tested-by: Alexander Stein <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
[ta: refine changes, new commit message, fix compilation error]
Signed-off-by: Tudor Ambarus <[email protected]>

Author: Louis Rannou

drivers/mtd/spi-nor/core.c

@@ -2026,6 +2026,15 @@ void spi_nor_set_erase_type(struct spi_nor_erase_type *erase, u32 size,
 	erase->size_mask = (1 << erase->size_shift) - 1;
 }
 
+/**
+ * spi_nor_mask_erase_type() - mask out a SPI NOR erase type
+ * @erase:	pointer to a structure that describes a SPI NOR erase type
+ */
+void spi_nor_mask_erase_type(struct spi_nor_erase_type *erase)
+{
+	erase->size = 0;
+}
+
 /**
  * spi_nor_init_uniform_erase_map() - Initialize uniform erase map
  * @map:		the erase map of the SPI NOR

drivers/mtd/spi-nor/core.h

@@ -681,6 +681,7 @@ void spi_nor_set_pp_settings(struct spi_nor_pp_command *pp, u8 opcode,
 
 void spi_nor_set_erase_type(struct spi_nor_erase_type *erase, u32 size,
 			    u8 opcode);
+void spi_nor_mask_erase_type(struct spi_nor_erase_type *erase);
 struct spi_nor_erase_region *
 spi_nor_region_next(struct spi_nor_erase_region *region);
 void spi_nor_init_uniform_erase_map(struct spi_nor_erase_map *map,

drivers/mtd/spi-nor/sfdp.c

@@ -875,7 +875,7 @@ static int spi_nor_init_non_uniform_erase_map(struct spi_nor *nor,
 	 */
 	for (i = 0; i < SNOR_ERASE_TYPE_MAX; i++)
 		if (!(regions_erase_type & BIT(erase[i].idx)))
-			spi_nor_set_erase_type(&erase[i], 0, 0xFF);
+			spi_nor_mask_erase_type(&erase[i]);
 
 	return 0;
 }
@@ -1089,7 +1089,7 @@ static int spi_nor_parse_4bait(struct spi_nor *nor,
 			erase_type[i].opcode = (dwords[SFDP_DWORD(2)] >>
 						erase_type[i].idx * 8) & 0xFF;
 		else
-			spi_nor_set_erase_type(&erase_type[i], 0u, 0xFF);
+			spi_nor_mask_erase_type(&erase_type[i]);
 	}
 
 	/*