Patch "mtd: cfi_cmdset_0001: Support the absence of protection registers" has been added to the 4.19-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    mtd: cfi_cmdset_0001: Support the absence of protection registers

to the 4.19-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     mtd-cfi_cmdset_0001-support-the-absence-of-protectio.patch
and it can be found in the queue-4.19 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit c79afde28327ed794191942f9407e078fba167d1
Author: Jean-Philippe Brucker <jean-philippe@xxxxxxxxxx>
Date:   Fri Apr 17 16:23:26 2020 +0200

    mtd: cfi_cmdset_0001: Support the absence of protection registers
    
    [ Upstream commit b359ed5184aebf9d987e54abc5dae7ac03ed29ae ]
    
    The flash controller implemented by the Arm Base platform behaves like
    the Intel StrataFlash J3 device, but omits several features. In
    particular it doesn't implement a protection register, so "Number of
    Protection register fields" in the Primary Vendor-Specific Extended
    Query, is 0.
    
    The Intel StrataFlash J3 datasheet only lists 1 as a valid value for
    NumProtectionFields. It describes the field as:
    
            "Number of Protection register fields in JEDEC ID space.
            “00h,” indicates that 256 protection bytes are available"
    
    While a value of 0 may arguably not be architecturally valid, the
    driver's current behavior is certainly wrong: if NumProtectionFields is
    0, read_pri_intelext() adds a negative value to the unsigned extra_size,
    and ends up in an infinite loop.
    
    Fix it by ignoring a NumProtectionFields of 0.
    
    Signed-off-by: Jean-Philippe Brucker <jean-philippe@xxxxxxxxxx>
    Tested-by: Sudeep Holla <sudeep.holla@xxxxxxx>
    Tested-by: Catalin Marinas <catalin.marinas@xxxxxxx>
    Signed-off-by: Vignesh Raghavendra <vigneshr@xxxxxx>
    Stable-dep-of: 565fe150624e ("mtd: cfi_cmdset_0001: Byte swap OTP info")
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/mtd/chips/cfi_cmdset_0001.c b/drivers/mtd/chips/cfi_cmdset_0001.c
index 6e8e7b1bb34b6..e5cf4911a714a 100644
--- a/drivers/mtd/chips/cfi_cmdset_0001.c
+++ b/drivers/mtd/chips/cfi_cmdset_0001.c
@@ -420,8 +420,9 @@ read_pri_intelext(struct map_info *map, __u16 adr)
 		extra_size = 0;
 
 		/* Protection Register info */
-		extra_size += (extp->NumProtectionFields - 1) *
-			      sizeof(struct cfi_intelext_otpinfo);
+		if (extp->NumProtectionFields)
+			extra_size += (extp->NumProtectionFields - 1) *
+				      sizeof(struct cfi_intelext_otpinfo);
 	}
 
 	if (extp->MinorVersion >= '1') {
@@ -695,14 +696,16 @@ static int cfi_intelext_partition_fixup(struct mtd_info *mtd,
 	 */
 	if (extp && extp->MajorVersion == '1' && extp->MinorVersion >= '3'
 	    && extp->FeatureSupport & (1 << 9)) {
+		int offs = 0;
 		struct cfi_private *newcfi;
 		struct flchip *chip;
 		struct flchip_shared *shared;
-		int offs, numregions, numparts, partshift, numvirtchips, i, j;
+		int numregions, numparts, partshift, numvirtchips, i, j;
 
 		/* Protection Register info */
-		offs = (extp->NumProtectionFields - 1) *
-		       sizeof(struct cfi_intelext_otpinfo);
+		if (extp->NumProtectionFields)
+			offs = (extp->NumProtectionFields - 1) *
+			       sizeof(struct cfi_intelext_otpinfo);
 
 		/* Burst Read info */
 		offs += extp->extra[offs+1]+2;