From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Ard Biesheuvel <ardb@kernel.org>,
Andy Lutomirski <luto@kernel.org>,
Ard Biesheuvel <ard.biesheuvel@linaro.org>,
Arvind Sankar <nivedita@alum.mit.edu>,
Matthew Garrett <mjg59@google.com>,
linux-efi@vger.kernel.org, Ingo Molnar <mingo@kernel.org>,
Sasha Levin <sashal@kernel.org>,
platform-driver-x86@vger.kernel.org, x86@kernel.org
Subject: [PATCH AUTOSEL 4.4 008/100] efi/x86: Map the entire EFI vendor string before copying it
Date: Fri, 14 Feb 2020 11:22:52 -0500 [thread overview]
Message-ID: <20200214162425.21071-8-sashal@kernel.org> (raw)
In-Reply-To: <20200214162425.21071-1-sashal@kernel.org>
From: Ard Biesheuvel <ardb@kernel.org>
[ Upstream commit ffc2760bcf2dba0dbef74013ed73eea8310cc52c ]
Fix a couple of issues with the way we map and copy the vendor string:
- we map only 2 bytes, which usually works since you get at least a
page, but if the vendor string happens to cross a page boundary,
a crash will result
- only call early_memunmap() if early_memremap() succeeded, or we will
call it with a NULL address which it doesn't like,
- while at it, switch to early_memremap_ro(), and array indexing rather
than pointer dereferencing to read the CHAR16 characters.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Arvind Sankar <nivedita@alum.mit.edu>
Cc: Matthew Garrett <mjg59@google.com>
Cc: linux-efi@vger.kernel.org
Fixes: 5b83683f32b1 ("x86: EFI runtime service support")
Link: https://lkml.kernel.org/r/20200103113953.9571-5-ardb@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/x86/platform/efi/efi.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)
diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
index 4bc352fc08f19..105872617be08 100644
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -465,7 +465,6 @@ void __init efi_init(void)
efi_char16_t *c16;
char vendor[100] = "unknown";
int i = 0;
- void *tmp;
#ifdef CONFIG_X86_32
if (boot_params.efi_info.efi_systab_hi ||
@@ -490,14 +489,16 @@ void __init efi_init(void)
/*
* Show what we know for posterity
*/
- c16 = tmp = early_memremap(efi.systab->fw_vendor, 2);
+ c16 = early_memremap_ro(efi.systab->fw_vendor,
+ sizeof(vendor) * sizeof(efi_char16_t));
if (c16) {
- for (i = 0; i < sizeof(vendor) - 1 && *c16; ++i)
- vendor[i] = *c16++;
+ for (i = 0; i < sizeof(vendor) - 1 && c16[i]; ++i)
+ vendor[i] = c16[i];
vendor[i] = '\0';
- } else
+ early_memunmap(c16, sizeof(vendor) * sizeof(efi_char16_t));
+ } else {
pr_err("Could not map the firmware vendor!\n");
- early_memunmap(tmp, 2);
+ }
pr_info("EFI v%u.%.02u by %s\n",
efi.systab->hdr.revision >> 16,
--
2.20.1
parent reply other threads:[~2020-02-14 16:35 UTC|newest]
Thread overview: expand[flat|nested] mbox.gz Atom feed
[parent not found: <20200214162425.21071-1-sashal@kernel.org>]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200214162425.21071-8-sashal@kernel.org \
--to=sashal@kernel.org \
--cc=ard.biesheuvel@linaro.org \
--cc=ardb@kernel.org \
--cc=linux-efi@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=luto@kernel.org \
--cc=mingo@kernel.org \
--cc=mjg59@google.com \
--cc=nivedita@alum.mit.edu \
--cc=platform-driver-x86@vger.kernel.org \
--cc=stable@vger.kernel.org \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).