On 2018/10/23 03:29, Konrad Rzeszutek Wilk wrote: > On Sat, Sep 22, 2018 at 08:56:58PM +0800, He Zhe wrote: >> May I have your input? > Alternatively would it make more sense for it to assume some default > value?
Maybe, but the original code has no default value and I have no idea what default value is proper here. Zhe >> Thanks, >> Zhe >> >> On 2018年09月17日 11:27, [email protected] wrote: >>> From: He Zhe <[email protected]> >>> >>> 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 <[email protected]> >>> Cc: [email protected] >>> Cc: [email protected] >>> Cc: [email protected] >>> Cc: [email protected] >>> Cc: [email protected] >>> --- >>> 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 */ >> _______________________________________________ >> iommu mailing list >> [email protected] >> https://lists.linuxfoundation.org/mailman/listinfo/iommu _______________________________________________ iommu mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/iommu
