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fix error with live debugging

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Signed-off-by: chenhaixiang <chenhaixiang3@huawei.com>
This commit is contained in:
chenhaixiang 2022-11-21 14:20:40 +08:00
parent 897c821826
commit 6eac679884
2 changed files with 63 additions and 1 deletions
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57
Fix-live-debugging-with-lockdown-integrity.patch Normal file
View File

@ -0,0 +1,57 @@
From e90c0011d6e9476104c4c43aa76d2d0830a15946 Mon Sep 17 00:00:00 2001
From: Philipp Rudo <prudo@redhat.com>
Date: Tue, 9 Nov 2021 14:52:22 +0100
Subject: [PATCH] Fix live debugging with lockdown=integrity
With kernel lockdown the access to kernel interfaces that allow to
extract confidential information (lockdown=confidentiality) or modify a
running kernel (lockdown=integrity) can be restricted. Two of the
interfaces that can be restricted are /dev/mem (integrity &
confidentiality) and /proc/kcore (confidentiality). With
lockdown=integrity this leads to a situation where /dev/mem exists but
is not readable while /proc/kcore exists and is readable. This breaks
crash's live debugging when it is invoked without argument, i.e.
$ crash
[...]
crash: /dev/mem: Operation not permitted
while passing /proc/kcore as image succeeds. The reason for this is that
crash always picks /dev/mem as source when it exits but doesn't check if
it is readable. Fix this by only selecting /dev/mem when it is readable.
Signed-off-by: Philipp Rudo <prudo@redhat.com>
---
filesys.c | 2 +-
main.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/filesys.c b/filesys.c
index 3361b6c..43cbe82 100644
--- a/filesys.c
+++ b/filesys.c
@@ -3666,7 +3666,7 @@ get_live_memory_source(void)
if (pc->live_memsrc)
goto live_report;
- if (file_exists("/dev/mem", NULL))
+ if (file_readable("/dev/mem"))
pc->live_memsrc = "/dev/mem";
else if (file_exists("/proc/kcore", NULL)) {
pc->flags &= ~DEVMEM;
diff --git a/main.c b/main.c
index 388ac46..dfd343c 100644
--- a/main.c
+++ b/main.c
@@ -1119,7 +1119,7 @@ setup_environment(int argc, char **argv)
pc->flags2 |= REDZONE;
pc->confd = -2;
pc->machine_type = MACHINE_TYPE;
- if (file_exists("/dev/mem", NULL)) { /* defaults until argv[] is parsed */
+ if (file_readable("/dev/mem")) { /* defaults until argv[] is parsed */
pc->readmem = read_dev_mem;
pc->writemem = write_dev_mem;
} else if (file_exists("/proc/kcore", NULL)) {
--
2.27.0

7
crash.spec
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@ -1,6 +1,6 @@
Name: crash
Version: 7.3.0
Release: 7
Release: 8
Summary: Linux kernel crash utility.
License: GPLv3
URL: https://crash-utility.github.io
@ -19,6 +19,7 @@ Patch9: 0002-CVE-2019-1010180-DWARF-reader-Reject-sections-with-invalid-sizes.pa
%ifarch sw_64
Patch10: crash-7.3.0-sw.patch
%endif
Patch11: Fix-live-debugging-with-lockdown-integrity.patch
BuildRequires: ncurses-devel zlib-devel lzo-devel snappy-devel
BuildRequires: gcc gcc-c++ bison m4
@ -84,6 +85,10 @@ install -D -m 0644 defs.h %{buildroot}%{_includedir}/%{name}/defs.h
%{_mandir}/man8/crash.8*
%changelog
* Mon Nov 21 2022 chenhaixiang <chenhaixiang3@huawei.com> - 7.3.0-8
- fix live debugging with error "cannot determine VA_BITS_ACTUAL:
please use /proc/kcore"
* Wed Oct 19 2022 wuzx<wuzx1226@qq.com> - 7.3.0-7
- add sw64 patch