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: 5c9c11e1c4 ("[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>
87a73eb5b5