regression: crash --minimal "log" command spins at 100% cpu after c86250bce29f Introduction of the "log -T" option
7:51 a.m.
This patch broke running "log" command when "crash --minimal" is
invoked for any vmcore. This is important because sometimes there is
a damaged vmcore and the log is enough to diagnose the problem.
It looks like this is the result of this code block where machdep->hz
== 0 and we divide by 0:
@@ -4936,6 +4939,15 @@ cmd_log(void)
if (argerrs)
cmd_usage(pc->curcmd, SYNOPSIS);
+ if (kt->boot_date.tv_sec == 0) {
+ ulonglong uptime_jiffies;
+ ulong uptime_sec;
+ get_uptime(NULL, &uptime_jiffies);
+ uptime_sec = (uptime_jiffies)/(ulonglong)machdep->hz;
+ kt->boot_date.tv_sec = kt->date.tv_sec - uptime_sec;
+ kt->boot_date.tv_nsec = 0;
+ }
+
I am not sure what the correct approach is here but wanted to report
this regression. Also wanted to ask whether this project has
considered any sort of CI tests to run on checkins.
Thanks.
9:10 a.m.
New subject: [PATCH] Fix "log" command when crash is stated with "--minimal" option
Commit c86250bce29f introduced the useful '-T' option to print the
log timestamp in human-readable form. However, this option does
not work when crash is invoked with '--minimal' mode, and if tried,
crash will spin at 100% and continuously crash at a divide by 0
because machdep->hz == 0.
Fix this by disallowing this option in minimal mode.
Further, only calculate the logic to calculate kt->boot_date.tv_sec
when this option is enabled.
Fixes: c86250bce29f ("Introduction of the "log -T" option...")
Signed-off-by: Dave Wysochanski <dwysocha(a)redhat.com>
---
kernel.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/kernel.c b/kernel.c
index 5ed6021..500532a 100644
--- a/kernel.c
+++ b/kernel.c
@@ -4939,7 +4939,11 @@ cmd_log(void)
if (argerrs)
cmd_usage(pc->curcmd, SYNOPSIS);
- if (kt->boot_date.tv_sec == 0) {
+ if (msg_flags & SHOW_LOG_CTIME && pc->flags & MINIMAL_MODE)
+ error(FATAL,
+ "log: option 'T' not available in minimal mode\n");
+
+ if (msg_flags & SHOW_LOG_CTIME && kt->boot_date.tv_sec == 0) {
ulonglong uptime_jiffies;
ulong uptime_sec;
get_uptime(NULL, &uptime_jiffies);
--
2.18.2
6:26 a.m.
New subject: [PATCH] Fix "log" command when crash is stated with "--minimal" option
Am 04.08.20 um 16:10 schrieb Dave Wysochanski:
Commit c86250bce29f introduced the useful '-T' option to
print the
log timestamp in human-readable form. However, this option does
not work when crash is invoked with '--minimal' mode, and if tried,
crash will spin at 100% and continuously crash at a divide by 0
because machdep->hz == 0.
Fix this by disallowing this option in minimal mode.
Further, only calculate the logic to calculate kt->boot_date.tv_sec
I guess the tab is not intended? -----------------^
when this option is enabled.
Fixes: c86250bce29f ("Introduction of the "log -T" option...")
Signed-off-by: Dave Wysochanski <dwysocha(a)redhat.com>
---
kernel.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/kernel.c b/kernel.c
index 5ed6021..500532a 100644
--- a/kernel.c
+++ b/kernel.c
@@ -4939,7 +4939,11 @@ cmd_log(void)
if (argerrs)
cmd_usage(pc->curcmd, SYNOPSIS);
- if (kt->boot_date.tv_sec == 0) {
+ if (msg_flags & SHOW_LOG_CTIME && pc->flags & MINIMAL_MODE)
+ error(FATAL,
+ "log: option 'T' not available in minimal mode\n");
Minor nit: no need to wrap the line, it fits the 80 columns limit just fine.
+
+ if (msg_flags & SHOW_LOG_CTIME && kt->boot_date.tv_sec == 0) {
ulonglong uptime_jiffies;
ulong uptime_sec;
get_uptime(NULL, &uptime_jiffies);
Beside that: Tested-by: Mathias Krause <minipli(a)grsecurity.net>
Thanks,
Mathias
8:25 a.m.
New subject: [PATCH] Fix "log" command when crash is started with "--minimal" option
Commit c86250bce29f introduced the useful '-T' option to print the
log timestamp in human-readable form. However, this option does
not work when crash is invoked with '--minimal' mode, and if tried,
crash will spin at 100% and continuously crash at a divide by 0
because machdep->hz == 0.
Fix this by disallowing this option in minimal mode. In addition,
only calculate the logic to calculate kt->boot_date.tv_sec
when this option is enabled.
Fixes: c86250bce29f ("Introduction of the "log -T" option...")
Signed-off-by: Dave Wysochanski <dwysocha(a)redhat.com>
---
kernel.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/kernel.c b/kernel.c
index 5ed6021..95119f3 100644
--- a/kernel.c
+++ b/kernel.c
@@ -4939,7 +4939,10 @@ cmd_log(void)
if (argerrs)
cmd_usage(pc->curcmd, SYNOPSIS);
- if (kt->boot_date.tv_sec == 0) {
+ if (msg_flags & SHOW_LOG_CTIME && pc->flags & MINIMAL_MODE)
+ error(FATAL, "log: option 'T' not available in minimal mode\n");
+
+ if (msg_flags & SHOW_LOG_CTIME && kt->boot_date.tv_sec == 0) {
ulonglong uptime_jiffies;
ulong uptime_sec;
get_uptime(NULL, &uptime_jiffies);
--
2.27.0
8:28 a.m.
New subject: [PATCH] Fix "log" command when crash is started with "--minimal" option
On Thu, Aug 6, 2020 at 9:25 AM Dave Wysochanski <dwysocha(a)redhat.com> wrote:
Commit c86250bce29f introduced the useful '-T' option to print the
log timestamp in human-readable form. However, this option does
not work when crash is invoked with '--minimal' mode, and if tried,
crash will spin at 100% and continuously crash at a divide by 0
because machdep->hz == 0.
Fix this by disallowing this option in minimal mode. In addition,
only calculate the logic to calculate kt->boot_date.tv_sec
when this option is enabled.
Fixes: c86250bce29f ("Introduction of the "log -T" option...")
Signed-off-by: Dave Wysochanski <dwysocha(a)redhat.com>
---
kernel.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/kernel.c b/kernel.c
index 5ed6021..95119f3 100644
--- a/kernel.c
+++ b/kernel.c
@@ -4939,7 +4939,10 @@ cmd_log(void)
if (argerrs)
cmd_usage(pc->curcmd, SYNOPSIS);
- if (kt->boot_date.tv_sec == 0) {
+ if (msg_flags & SHOW_LOG_CTIME && pc->flags & MINIMAL_MODE)
+ error(FATAL, "log: option 'T' not available in minimal
mode\n");
+
+ if (msg_flags & SHOW_LOG_CTIME && kt->boot_date.tv_sec == 0) {
ulonglong uptime_jiffies;
ulong uptime_sec;
get_uptime(NULL, &uptime_jiffies);
--
2.27.0
--
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Thanks
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1427
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4 comments
3 participants
participants (3)
-
Dave Wysochanski -
David Wysochanski
-
Mathias Krause