Messages in this thread | | | Subject | Re: [PATCH v3 1/2] printk: Fix panic caused by passing log_buf_len to command line | From | He Zhe <> | Date | Sun, 23 Sep 2018 14:51:12 +0800 |
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On 2018年09月23日 00:19, Steven Rostedt wrote: > On Sat, 22 Sep 2018 23:40:51 +0800 > <zhe.he@windriver.com> wrote: > >> From: He Zhe <zhe.he@windriver.com> >> >> log_buf_len_setup does not check input argument before passing it to >> simple_strtoull. The argument would be a NULL pointer if "log_buf_len", >> without its value, is set in command line and thus causes the following >> panic. >> >> PANIC: early exception 0xe3 IP 10:ffffffffaaeacd0d error 0 cr2 0x0 >> [ 0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 4.19.0-rc4-yocto-standard+ #1 >> [ 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] log_buf_len_setup+0x17/0x22 >> [ 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/0x4ee >> [ 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 > I just tried this on a 2.6.32 kernel, and it crashes there. I guess > this goes farther back than git history goes. > > Perhaps it should be commented that this bug has been here since > creation of (git) time.
I did a try on 2.6.32. It passed. Actually this bug only happens on early_param(not __setup) which is introduced since v3.0. The oldest LTS version is 3.16 now. Should I send v4 and add a statement about the supported version range in commit log?
> > >> Cc: pmladek@suse.com >> Cc: sergey.senozhatsky@gmail.com >> Cc: rostedt@goodmis.org >> --- >> v2: >> Split out the addition of pr_fmt and the unsigned update > Which unsigned update? As it does switch to unsigned to "unsigned int", > but that change is fine to me with this.
No problem. It's the history of v2.
In v1 you suggested "unsigned int size" should be in a separate patch and I did that in v2. Then Sergey suggested "unsigned int size" should be in the 1/2 patch to avoid checkpatch.pl warning. With your conformation, I add it back here in v3.
Thanks, Zhe
> >> v3: >> Use more clear error info >> Change unsigned to unsigned in to avoid checkpatch.pl warning >> >> kernel/printk/printk.c | 9 ++++++++- >> 1 file changed, 8 insertions(+), 1 deletion(-) >> >> diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c >> index 9bf5404..d9821c0 100644 >> --- a/kernel/printk/printk.c >> +++ b/kernel/printk/printk.c >> @@ -1048,7 +1048,14 @@ static void __init log_buf_len_update(unsigned size) >> /* save requested log_buf_len since it's too early to process it */ >> static int __init log_buf_len_setup(char *str) >> { >> - unsigned size = memparse(str, &str); >> + unsigned int size; > I'm OK with the int update too, as its low risk. > > Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> > > -- Steve > >> + >> + if (!str) { >> + pr_err("boot command line parameter value not provided\n"); >> + return -EINVAL; >> + } >> + >> + size = memparse(str, &str); >> >> log_buf_len_update(size); >> >
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