Patch "mtd: jedec_probe: Fix crash in jedec_read_mfr()" has been added to the 4.15-stable tree

[<gregkh@linuxfoundation.org>]

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

    mtd: jedec_probe: Fix crash in jedec_read_mfr()

to the 4.15-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-jedec_probe-fix-crash-in-jedec_read_mfr.patch
and it can be found in the queue-4.15 subdirectory.

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


>From 87a73eb5b56fd6e07c8e499fe8608ef2d8912b82 Mon Sep 17 00:00:00 2001
From: Linus Walleij <linus.walleij@linaro.org>
Date: Sat, 3 Mar 2018 23:29:03 +0100
Subject: mtd: jedec_probe: Fix crash in jedec_read_mfr()

From: Linus Walleij <linus.walleij@linaro.org>

commit 87a73eb5b56fd6e07c8e499fe8608ef2d8912b82 upstream.

It turns out that the loop where we read manufacturer
jedec_read_mfd() can under some circumstances get a
CFI_MFR_CONTINUATION repeatedly, making the loop go
over all banks and eventually hit the end of the
map and crash because of an access violation:

Unable to handle kernel paging request at virtual address c4980000
pgd = (ptrval)
[c4980000] *pgd=03808811, *pte=00000000, *ppte=00000000
Internal error: Oops: 7 [#1] PREEMPT ARM
CPU: 0 PID: 1 Comm: swapper Not tainted 4.16.0-rc1+ #150
Hardware name: Gemini (Device Tree)
PC is at jedec_probe_chip+0x6ec/0xcd0
LR is at 0x4
pc : [<c03a2bf4>]    lr : [<00000004>]    psr: 60000013
sp : c382dd18  ip : 0000ffff  fp : 00000000
r10: c0626388  r9 : 00020000  r8 : c0626340
r7 : 00000000  r6 : 00000001  r5 : c3a71afc  r4 : c382dd70
r3 : 00000001  r2 : c4900000  r1 : 00000002  r0 : 00080000
Flags: nZCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment none
Control: 0000397f  Table: 00004000  DAC: 00000053
Process swapper (pid: 1, stack limit = 0x(ptrval))

Fix this by breaking the loop with a return 0 if
the offset exceeds the map size.

Fixes: 5c9c11e1c47c ("[MTD] [NOR] Add support for flash chips with ID in bank other than 0")
Cc: <stable@vger.kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/mtd/chips/jedec_probe.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/drivers/mtd/chips/jedec_probe.c
+++ b/drivers/mtd/chips/jedec_probe.c
@@ -1889,6 +1889,8 @@ static inline u32 jedec_read_mfr(struct
 	do {
 		uint32_t ofs = cfi_build_cmd_addr(0 + (bank << 8), map, cfi);
 		mask = (1 << (cfi->device_type * 8)) - 1;
+		if (ofs >= map->size)
+			return 0;
 		result = map_read(map, base + ofs);
 		bank++;
 	} while ((result.x[0] & mask) == CFI_MFR_CONTINUATION);


Patches currently in stable-queue which might be from linus.walleij@linaro.org are

queue-4.15/mtd-jedec_probe-fix-crash-in-jedec_read_mfr.patch