From e423c90a6520d704cd885d742b499dfd6b0f6277 Mon Sep 17 00:00:00 2001 From: Robert Jarzmik Date: Sun, 8 Feb 2015 21:02:09 +0100 Subject: [PATCH] mtd: pxa3xx_nand: fix driver when num_cs is 0 As the devicetree binding doesn't require num_cs to exist or be strictly positive, and neither does the platform data case, a bug appear when num_cs is set to 0 and panics the kernel. The issue is that in alloc_nand_resource(), chip is dereferenced without having a value assigned when num_cs == 0. Fix this by returning ENODEV is num_cs == 0. The panic seen is : Unable to handle kernel NULL pointer dereference at virtual address 000002b8 pgd = c0004000 [000002b8] *pgd=00000000 Internal error: Oops: 5 [#1] PREEMPT ARM Modules linked in: Hardware name: Marvell PXA3xx (Device Tree Support) task: c3822aa0 ti: c3826000 task.ti: c3826000 PC is at alloc_nand_resource+0x180/0x4a8 LR is at alloc_nand_resource+0xa0/0x4a8 pc : [] lr : [] psr: 68000013 sp : c3827d90 ip : 00000000 fp : 00000000 r10: c3862200 r9 : 0000005e r8 : 00000000 r7 : c3865610 r6 : c3862210 r5 : c3924210 r4 : c3862200 r3 : 00000000 r2 : 00000000 r1 : 00000000 r0 : 00000000 Flags: nZCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment kernel Control: 0000397f Table: 80004018 DAC: 00000035 Process swapper (pid: 1, stack limit = 0xc3826198) Stack: (0xc3827d90 to 0xc3828000) ...zip... [] (alloc_nand_resource) from [] (pxa3xx_nand_probe+0x140/0x978) [] (pxa3xx_nand_probe) from [] (platform_drv_probe+0x48/0xa4) [] (platform_drv_probe) from [] (driver_probe_device+0x80/0x21c) [] (driver_probe_device) from [] (__driver_attach+0x8c/0x90) [] (__driver_attach) from [] (bus_for_each_dev+0x58/0x88) [] (bus_for_each_dev) from [] (bus_add_driver+0xd8/0x1d4) [] (bus_add_driver) from [] (driver_register+0x78/0xf4) [] (driver_register) from [] (do_one_initcall+0x80/0x1e4) [] (do_one_initcall) from [] (kernel_init_freeable+0xec/0x1b4) [] (kernel_init_freeable) from [] (kernel_init+0x8/0xe4) [] (kernel_init) from [] (ret_from_fork+0x14/0x3c) Code: e503b234 e5953008 e1530001 caffffd1 (e59002b8) ---[ end trace a5770060c8441895 ]--- Signed-off-by: Robert Jarzmik Acked-by: Ezequiel Garcia Signed-off-by: Brian Norris --- drivers/mtd/nand/pxa3xx_nand.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/mtd/nand/pxa3xx_nand.c b/drivers/mtd/nand/pxa3xx_nand.c index bc677362bc73..10b1f7a4fe50 100644 --- a/drivers/mtd/nand/pxa3xx_nand.c +++ b/drivers/mtd/nand/pxa3xx_nand.c @@ -1608,6 +1608,8 @@ static int alloc_nand_resource(struct platform_device *pdev) int ret, irq, cs; pdata = dev_get_platdata(&pdev->dev); + if (pdata->num_cs <= 0) + return -ENODEV; info = devm_kzalloc(&pdev->dev, sizeof(*info) + (sizeof(*mtd) + sizeof(*host)) * pdata->num_cs, GFP_KERNEL); if (!info)