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 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: mtd-jedec_probe-fix-crash-in-jedec_read_mfr.patch and it can be found in the queue-4.4 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-4.4/mtd-jedec_probe-fix-crash-in-jedec_read_mfr.patch