Messages in this thread | | | From | Kees Cook <> | Date | Thu, 14 Dec 2017 17:05:14 -0800 | Subject | Re: [PATCH] APEI / ERST: Fix missing error handling in erst_reader() |
| |
On Thu, Dec 14, 2017 at 5:01 PM, Rafael J. Wysocki <rafael@kernel.org> wrote: > On Thu, Dec 14, 2017 at 1:31 PM, Takashi Iwai <tiwai@suse.de> wrote: >> The commit f6f828513290 ("pstore: pass allocated memory region back to >> caller") changed the check of the return value from erst_read() in >> erst_reader() in the following way: >> >> if (len == -ENOENT) >> goto skip; >> - else if (len < 0) { >> - rc = -1; >> + else if (len < sizeof(*rcd)) { >> + rc = -EIO; >> goto out; >> >> This introduced another bug: since the comparison with sizeof() is >> cast to unsigned, a negative len value doesn't hit any longer. >> As a result, when an error is returned from erst_read(), the code >> falls through, and it may eventually lead to some weird thing like >> memory corruption. >> >> This patch adds the negative error value check more explicitly for >> addressing the issue.
Ew, nice catch, thanks!
>> >> Fixes: f6f828513290 ("pstore: pass allocated memory region back to caller") > > That's ancient. :-) > >> Cc: <stable@vger.kernel.org> >> Tested-by: Jerry Tang <jtang@suse.com> >> Signed-off-by: Takashi Iwai <tiwai@suse.de> >> --- >> drivers/acpi/apei/erst.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/acpi/apei/erst.c b/drivers/acpi/apei/erst.c >> index 6742f6c68034..9bff853e85f3 100644 >> --- a/drivers/acpi/apei/erst.c >> +++ b/drivers/acpi/apei/erst.c >> @@ -1007,7 +1007,7 @@ static ssize_t erst_reader(struct pstore_record *record) >> /* The record may be cleared by others, try read next record */ >> if (len == -ENOENT) >> goto skip; >> - else if (len < sizeof(*rcd)) { >> + else if (len < 0 || len < sizeof(*rcd)) { >> rc = -EIO; >> goto out; >> } >> -- > > OK, I'm going to queue this up unless I see objections from Boris or Tony.
Please do, yes.
Acked-by: Kees Cook <keescook@chromium.org>
-Kees
-- Kees Cook Pixel Security
| |