4.18-stable review patch. If anyone has any objections, please let me know.
------------------
From: He Zhe <zhe.he@xxxxxxxxxxxxx>
commit a3ceed87b07769fb80ce9dc6b604e515dba14c4b upstream.
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>
Reviewed-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/dma/contiguous.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
--- a/kernel/dma/contiguous.c
+++ b/kernel/dma/contiguous.c
@@ -49,7 +49,11 @@ static phys_addr_t limit_cmdline;
static int __init early_cma(char *p)
{
- pr_debug("%s(%s)\n", __func__, p);
+ if (!p) {
+ pr_err("Config string not provided\n");
+ return -EINVAL;
+ }
+
size_cmdline = memparse(p, &p);
if (*p != '@')
return 0;
