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SubjectRe: [PATCH] kernel/dma: Fix panic caused by passing swiotlb to command line
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May I have your input?

Thanks,
Zhe

On 2018年09月17日 11:27, zhe.he@windriver.com wrote:
> From: He Zhe <zhe.he@windriver.com>
>
> setup_io_tlb_npages does not check input argument before passing it
> to isdigit. The argument would be a NULL pointer if "swiotlb", without
> its value, is set in command line and thus causes the following panic.
>
> PANIC: early exception 0xe3 IP 10:ffffffffbb9b8e9f error 0 cr2 0x0
> [ 0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 4.19.0-rc3-yocto-standard+ #9
> [ 0.000000] RIP: 0010:setup_io_tlb_npages+0xf/0x95
> ...
> [ 0.000000] Call Trace:
> [ 0.000000] do_early_param+0x57/0x8e
> [ 0.000000] parse_args+0x208/0x320
> [ 0.000000] ? rdinit_setup+0x30/0x30
> [ 0.000000] parse_early_options+0x29/0x2d
> [ 0.000000] ? rdinit_setup+0x30/0x30
> [ 0.000000] parse_early_param+0x36/0x4d
> [ 0.000000] setup_arch+0x336/0x99e
> [ 0.000000] start_kernel+0x6f/0x4e6
> [ 0.000000] x86_64_start_reservations+0x24/0x26
> [ 0.000000] x86_64_start_kernel+0x6f/0x72
> [ 0.000000] secondary_startup_64+0xa4/0xb0
>
> This patch adds a check to prevent the panic.
>
> Signed-off-by: He Zhe <zhe.he@windriver.com>
> Cc: stable@vger.kernel.org
> Cc: konrad.wilk@oracle.com
> Cc: hch@lst.de
> Cc: m.szyprowski@samsung.com
> Cc: robin.murphy@arm.com
> ---
> kernel/dma/swiotlb.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
> index 4f8a6db..46fc34e 100644
> --- a/kernel/dma/swiotlb.c
> +++ b/kernel/dma/swiotlb.c
> @@ -109,6 +109,11 @@ static int late_alloc;
> static int __init
> setup_io_tlb_npages(char *str)
> {
> + if (!str) {
> + pr_err("Config string not provided\n");
> + return -EINVAL;
> + }
> +
> if (isdigit(*str)) {
> io_tlb_nslabs = simple_strtoul(str, &str, 0);
> /* avoid tail segment of size < IO_TLB_SEGSIZE */

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