Re: [PATCH] kernel/dma: Fix panic caused by passing cma to command line

[Christoph Hellwig]

On Tue, Sep 18, 2018 at 11:28:33AM +0200, Marek Szyprowski wrote:
> Hi
> 
> On 2018-09-17 05:24, zhe.he@xxxxxxxxxxxxx wrote:
> > From: He Zhe <zhe.he@xxxxxxxxxxxxx>
> >
> > early_cma does not check input argument before passing it to
> > simple_strtoull. The argument would be a NULL pointer if "cma", without
> > its value, is set in command line and thus causes the following panic.
> >
> > PANIC: early exception 0xe3 IP 10:ffffffffa3e9db8d error 0 cr2 0x0
> > [    0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 4.19.0-rc3-yocto-standard+ #7
> > [    0.000000] RIP: 0010:_parse_integer_fixup_radix+0xd/0x70
> > ...
> > [    0.000000] Call Trace:
> > [    0.000000]  simple_strtoull+0x29/0x70
> > [    0.000000]  memparse+0x26/0x90
> > [    0.000000]  early_cma+0x17/0x6a
> > [    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@xxxxxxxxxxxxx>
> > Cc: stable@xxxxxxxxxxxxxxx
> > Cc: hch@xxxxxx
> > Cc: m.szyprowski@xxxxxxxxxxx
> > Cc: robin.murphy@xxxxxxx
> 
> Thanks for the fix.
> 
> Reviewed-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>

Thanks, added to the dma-mapping tree.