* [PATCH] vmcore-dmesg: Do not write beyond end of allocated buffer
@ 2012-07-17 15:23 Vivek Goyal
2012-07-17 22:40 ` Simon Horman
0 siblings, 1 reply; 6+ messages in thread
From: Vivek Goyal @ 2012-07-17 15:23 UTC (permalink / raw)
To: Kexec Mailing List, horms; +Cc: Eric W. Biederman
scan_vmcoreinfo() currently assumes that every line in vmcoreinfo note ends
with \n and overwrites new line character with \0. But last entry in note,
CRASHTIME= does not end with \n and this leads to corrupting memory as we
write beyond end of buffer.
Normally things were fine but when I added some fields to vmcoreinfo, this
bug started showing and vmcore-dmesg started crashing.
I am planning to send a patch to fix this in kernel but it might be good
idea to handle this case in user space too so that vmcore-dmesg works
fine with cores of older kernels.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
---
vmcore-dmesg/vmcore-dmesg.c | 27 ++++++++++++++++++++++++++-
1 file changed, 26 insertions(+), 1 deletion(-)
Index: kexec-tools/vmcore-dmesg/vmcore-dmesg.c
===================================================================
--- kexec-tools.orig/vmcore-dmesg/vmcore-dmesg.c 2012-07-19 01:54:02.700700235 -0400
+++ kexec-tools/vmcore-dmesg/vmcore-dmesg.c 2012-07-19 01:55:08.232702248 -0400
@@ -14,6 +14,7 @@
#include <sys/stat.h>
#include <fcntl.h>
#include <elf.h>
+#include <stdbool.h>
/* The 32bit and 64bit note headers make it clear we don't care */
typedef Elf32_Nhdr Elf_Nhdr;
@@ -220,6 +221,9 @@ static void scan_vmcoreinfo(char *start,
{
char *last = start + size - 1;
char *pos, *eol;
+ char temp_buf[1024];
+ bool last_line = false;
+
#define SYMBOL(sym) { \
.str = "SYMBOL(" #sym ")=", \
.name = #sym, \
@@ -243,7 +247,25 @@ static void scan_vmcoreinfo(char *start,
/* Find the end of the current line */
for (eol = pos; (eol <= last) && (*eol != '\n') ; eol++)
;
- len = eol - pos + 1;
+ if (eol > last) {
+ /*
+ * We did not find \n and note ended. Currently kernel
+ * is appending last field CRASH_TIME without \n. It
+ * is ugly but handle it.
+ */
+ eol = last;
+ len = eol - pos + 1;
+ strncpy(temp_buf, pos, len);
+ temp_buf[len + 1] = '\0';
+
+ pos = temp_buf;
+ len = len + 1;
+ eol = pos + len -1;
+ last_line = true;
+ } else {
+ len = eol - pos + 1;
+ }
+
/* Stomp the last character so I am guaranteed a terminating null */
*eol = '\0';
/* Copy OSRELEASE if I see it */
@@ -266,6 +288,9 @@ static void scan_vmcoreinfo(char *start,
/* Remember the virtual address */
*symbol[i].vaddr = vaddr;
}
+
+ if (last_line)
+ break;
}
}
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] vmcore-dmesg: Do not write beyond end of allocated buffer
2012-07-17 15:23 [PATCH] vmcore-dmesg: Do not write beyond end of allocated buffer Vivek Goyal
@ 2012-07-17 22:40 ` Simon Horman
2012-07-18 13:33 ` Vivek Goyal
0 siblings, 1 reply; 6+ messages in thread
From: Simon Horman @ 2012-07-17 22:40 UTC (permalink / raw)
To: Vivek Goyal; +Cc: Kexec Mailing List, Eric W. Biederman
On Tue, Jul 17, 2012 at 11:23:00AM -0400, Vivek Goyal wrote:
> scan_vmcoreinfo() currently assumes that every line in vmcoreinfo note ends
> with \n and overwrites new line character with \0. But last entry in note,
> CRASHTIME= does not end with \n and this leads to corrupting memory as we
> write beyond end of buffer.
>
> Normally things were fine but when I added some fields to vmcoreinfo, this
> bug started showing and vmcore-dmesg started crashing.
>
> I am planning to send a patch to fix this in kernel but it might be good
> idea to handle this case in user space too so that vmcore-dmesg works
> fine with cores of older kernels.
Good plan.
> Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
> ---
> vmcore-dmesg/vmcore-dmesg.c | 27 ++++++++++++++++++++++++++-
> 1 file changed, 26 insertions(+), 1 deletion(-)
>
> Index: kexec-tools/vmcore-dmesg/vmcore-dmesg.c
> ===================================================================
> --- kexec-tools.orig/vmcore-dmesg/vmcore-dmesg.c 2012-07-19 01:54:02.700700235 -0400
> +++ kexec-tools/vmcore-dmesg/vmcore-dmesg.c 2012-07-19 01:55:08.232702248 -0400
> @@ -14,6 +14,7 @@
> #include <sys/stat.h>
> #include <fcntl.h>
> #include <elf.h>
> +#include <stdbool.h>
>
> /* The 32bit and 64bit note headers make it clear we don't care */
> typedef Elf32_Nhdr Elf_Nhdr;
> @@ -220,6 +221,9 @@ static void scan_vmcoreinfo(char *start,
> {
> char *last = start + size - 1;
> char *pos, *eol;
> + char temp_buf[1024];
> + bool last_line = false;
Is there a chance of over-running temp_buf?
I would be more comfortable if there was a check below to
ensure that len can never be greater than sizeof(temp_buf).
> +
> #define SYMBOL(sym) { \
> .str = "SYMBOL(" #sym ")=", \
> .name = #sym, \
> @@ -243,7 +247,25 @@ static void scan_vmcoreinfo(char *start,
> /* Find the end of the current line */
> for (eol = pos; (eol <= last) && (*eol != '\n') ; eol++)
> ;
> - len = eol - pos + 1;
> + if (eol > last) {
> + /*
> + * We did not find \n and note ended. Currently kernel
> + * is appending last field CRASH_TIME without \n. It
> + * is ugly but handle it.
> + */
> + eol = last;
> + len = eol - pos + 1;
> + strncpy(temp_buf, pos, len);
> + temp_buf[len + 1] = '\0';
> +
> + pos = temp_buf;
> + len = len + 1;
> + eol = pos + len -1;
> + last_line = true;
> + } else {
> + len = eol - pos + 1;
> + }
> +
> /* Stomp the last character so I am guaranteed a terminating null */
> *eol = '\0';
> /* Copy OSRELEASE if I see it */
> @@ -266,6 +288,9 @@ static void scan_vmcoreinfo(char *start,
> /* Remember the virtual address */
> *symbol[i].vaddr = vaddr;
> }
> +
> + if (last_line)
> + break;
> }
> }
>
>
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] vmcore-dmesg: Do not write beyond end of allocated buffer
2012-07-17 22:40 ` Simon Horman
@ 2012-07-18 13:33 ` Vivek Goyal
2012-07-23 14:35 ` Vivek Goyal
2012-07-24 0:34 ` Simon Horman
0 siblings, 2 replies; 6+ messages in thread
From: Vivek Goyal @ 2012-07-18 13:33 UTC (permalink / raw)
To: Simon Horman; +Cc: Kexec Mailing List, Eric W. Biederman
On Wed, Jul 18, 2012 at 07:40:32AM +0900, Simon Horman wrote:
> On Tue, Jul 17, 2012 at 11:23:00AM -0400, Vivek Goyal wrote:
> > scan_vmcoreinfo() currently assumes that every line in vmcoreinfo note ends
> > with \n and overwrites new line character with \0. But last entry in note,
> > CRASHTIME= does not end with \n and this leads to corrupting memory as we
> > write beyond end of buffer.
> >
> > Normally things were fine but when I added some fields to vmcoreinfo, this
> > bug started showing and vmcore-dmesg started crashing.
> >
> > I am planning to send a patch to fix this in kernel but it might be good
> > idea to handle this case in user space too so that vmcore-dmesg works
> > fine with cores of older kernels.
>
> Good plan.
>
> > Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
> > ---
> > vmcore-dmesg/vmcore-dmesg.c | 27 ++++++++++++++++++++++++++-
> > 1 file changed, 26 insertions(+), 1 deletion(-)
> >
> > Index: kexec-tools/vmcore-dmesg/vmcore-dmesg.c
> > ===================================================================
> > --- kexec-tools.orig/vmcore-dmesg/vmcore-dmesg.c 2012-07-19 01:54:02.700700235 -0400
> > +++ kexec-tools/vmcore-dmesg/vmcore-dmesg.c 2012-07-19 01:55:08.232702248 -0400
> > @@ -14,6 +14,7 @@
> > #include <sys/stat.h>
> > #include <fcntl.h>
> > #include <elf.h>
> > +#include <stdbool.h>
> >
> > /* The 32bit and 64bit note headers make it clear we don't care */
> > typedef Elf32_Nhdr Elf_Nhdr;
> > @@ -220,6 +221,9 @@ static void scan_vmcoreinfo(char *start,
> > {
> > char *last = start + size - 1;
> > char *pos, *eol;
> > + char temp_buf[1024];
> > + bool last_line = false;
>
> Is there a chance of over-running temp_buf?
>
> I would be more comfortable if there was a check below to
> ensure that len can never be greater than sizeof(temp_buf).
Hi Simon,
Agreed. Making sure temp_buf does not overflow is a good idea. Here is
the udpated patch.
Thanks
Vivek
vmcore-dmesg: Do not write beyond end of buffer
scan_vmcoreinfo() currently assumes that every vmcoreinfo note line ends
with \n and overwrites new line with \0. But last entry in note, CRASHTIME=
does not end with \n and this leads to corrupting memory as we write beyond
end of buffer.
Normally things were fine but when I added some fields to vmcoreinfo, this
bug started showing and vmcore-dmesg started crashing.
I am planning to send a patch to fix this in kernel but it might be good
idea to handle this case in user space too so that vmcore-dmesg works
fine with cores of older kernels.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
---
vmcore-dmesg/vmcore-dmesg.c | 29 ++++++++++++++++++++++++++++-
1 file changed, 28 insertions(+), 1 deletion(-)
Index: kexec-tools/vmcore-dmesg/vmcore-dmesg.c
===================================================================
--- kexec-tools.orig/vmcore-dmesg/vmcore-dmesg.c 2012-07-20 08:04:42.370051049 -0400
+++ kexec-tools/vmcore-dmesg/vmcore-dmesg.c 2012-07-20 08:12:14.198070252 -0400
@@ -14,6 +14,7 @@
#include <sys/stat.h>
#include <fcntl.h>
#include <elf.h>
+#include <stdbool.h>
/* The 32bit and 64bit note headers make it clear we don't care */
typedef Elf32_Nhdr Elf_Nhdr;
@@ -220,6 +221,9 @@ static void scan_vmcoreinfo(char *start,
{
char *last = start + size - 1;
char *pos, *eol;
+ char temp_buf[1024];
+ bool last_line = false;
+
#define SYMBOL(sym) { \
.str = "SYMBOL(" #sym ")=", \
.name = #sym, \
@@ -243,7 +247,27 @@ static void scan_vmcoreinfo(char *start,
/* Find the end of the current line */
for (eol = pos; (eol <= last) && (*eol != '\n') ; eol++)
;
- len = eol - pos + 1;
+ if (eol > last) {
+ /*
+ * We did not find \n and note ended. Currently kernel
+ * is appending last field CRASH_TIME without \n. It
+ * is ugly but handle it.
+ */
+ eol = last;
+ len = eol - pos + 1;
+ if (len >= sizeof(temp_buf))
+ len = sizeof(temp_buf) - 1;
+ strncpy(temp_buf, pos, len);
+ temp_buf[len + 1] = '\0';
+
+ pos = temp_buf;
+ len = len + 1;
+ eol = pos + len -1;
+ last_line = true;
+ } else {
+ len = eol - pos + 1;
+ }
+
/* Stomp the last character so I am guaranteed a terminating null */
*eol = '\0';
/* Copy OSRELEASE if I see it */
@@ -266,6 +290,9 @@ static void scan_vmcoreinfo(char *start,
/* Remember the virtual address */
*symbol[i].vaddr = vaddr;
}
+
+ if (last_line)
+ break;
}
}
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http://lists.infradead.org/mailman/listinfo/kexec
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] vmcore-dmesg: Do not write beyond end of allocated buffer
2012-07-18 13:33 ` Vivek Goyal
@ 2012-07-23 14:35 ` Vivek Goyal
2012-07-23 23:08 ` Simon Horman
2012-07-24 0:34 ` Simon Horman
1 sibling, 1 reply; 6+ messages in thread
From: Vivek Goyal @ 2012-07-23 14:35 UTC (permalink / raw)
To: Simon Horman; +Cc: Kexec Mailing List, Eric W. Biederman
On Wed, Jul 18, 2012 at 09:33:51AM -0400, Vivek Goyal wrote:
[..]
> > > + char temp_buf[1024];
> > > + bool last_line = false;
> >
> > Is there a chance of over-running temp_buf?
> >
> > I would be more comfortable if there was a check below to
> > ensure that len can never be greater than sizeof(temp_buf).
>
> Hi Simon,
>
> Agreed. Making sure temp_buf does not overflow is a good idea. Here is
> the udpated patch.
>
Hi Simon,
Do you have any more concerns with this patch. If not, can you please
apply it.
Thanks
Vivek
> Thanks
> Vivek
>
>
> vmcore-dmesg: Do not write beyond end of buffer
>
> scan_vmcoreinfo() currently assumes that every vmcoreinfo note line ends
> with \n and overwrites new line with \0. But last entry in note, CRASHTIME=
> does not end with \n and this leads to corrupting memory as we write beyond
> end of buffer.
>
> Normally things were fine but when I added some fields to vmcoreinfo, this
> bug started showing and vmcore-dmesg started crashing.
>
> I am planning to send a patch to fix this in kernel but it might be good
> idea to handle this case in user space too so that vmcore-dmesg works
> fine with cores of older kernels.
>
> Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
> ---
> vmcore-dmesg/vmcore-dmesg.c | 29 ++++++++++++++++++++++++++++-
> 1 file changed, 28 insertions(+), 1 deletion(-)
>
> Index: kexec-tools/vmcore-dmesg/vmcore-dmesg.c
> ===================================================================
> --- kexec-tools.orig/vmcore-dmesg/vmcore-dmesg.c 2012-07-20 08:04:42.370051049 -0400
> +++ kexec-tools/vmcore-dmesg/vmcore-dmesg.c 2012-07-20 08:12:14.198070252 -0400
> @@ -14,6 +14,7 @@
> #include <sys/stat.h>
> #include <fcntl.h>
> #include <elf.h>
> +#include <stdbool.h>
>
> /* The 32bit and 64bit note headers make it clear we don't care */
> typedef Elf32_Nhdr Elf_Nhdr;
> @@ -220,6 +221,9 @@ static void scan_vmcoreinfo(char *start,
> {
> char *last = start + size - 1;
> char *pos, *eol;
> + char temp_buf[1024];
> + bool last_line = false;
> +
> #define SYMBOL(sym) { \
> .str = "SYMBOL(" #sym ")=", \
> .name = #sym, \
> @@ -243,7 +247,27 @@ static void scan_vmcoreinfo(char *start,
> /* Find the end of the current line */
> for (eol = pos; (eol <= last) && (*eol != '\n') ; eol++)
> ;
> - len = eol - pos + 1;
> + if (eol > last) {
> + /*
> + * We did not find \n and note ended. Currently kernel
> + * is appending last field CRASH_TIME without \n. It
> + * is ugly but handle it.
> + */
> + eol = last;
> + len = eol - pos + 1;
> + if (len >= sizeof(temp_buf))
> + len = sizeof(temp_buf) - 1;
> + strncpy(temp_buf, pos, len);
> + temp_buf[len + 1] = '\0';
> +
> + pos = temp_buf;
> + len = len + 1;
> + eol = pos + len -1;
> + last_line = true;
> + } else {
> + len = eol - pos + 1;
> + }
> +
> /* Stomp the last character so I am guaranteed a terminating null */
> *eol = '\0';
> /* Copy OSRELEASE if I see it */
> @@ -266,6 +290,9 @@ static void scan_vmcoreinfo(char *start,
> /* Remember the virtual address */
> *symbol[i].vaddr = vaddr;
> }
> +
> + if (last_line)
> + break;
> }
> }
>
>
> _______________________________________________
> kexec mailing list
> kexec@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/kexec
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] vmcore-dmesg: Do not write beyond end of allocated buffer
2012-07-23 14:35 ` Vivek Goyal
@ 2012-07-23 23:08 ` Simon Horman
0 siblings, 0 replies; 6+ messages in thread
From: Simon Horman @ 2012-07-23 23:08 UTC (permalink / raw)
To: Vivek Goyal; +Cc: Kexec Mailing List, Eric W. Biederman
On Mon, Jul 23, 2012 at 10:35:12AM -0400, Vivek Goyal wrote:
> On Wed, Jul 18, 2012 at 09:33:51AM -0400, Vivek Goyal wrote:
>
> [..]
> > > > + char temp_buf[1024];
> > > > + bool last_line = false;
> > >
> > > Is there a chance of over-running temp_buf?
> > >
> > > I would be more comfortable if there was a check below to
> > > ensure that len can never be greater than sizeof(temp_buf).
> >
> > Hi Simon,
> >
> > Agreed. Making sure temp_buf does not overflow is a good idea. Here is
> > the udpated patch.
> >
>
> Hi Simon,
>
> Do you have any more concerns with this patch. If not, can you please
> apply it.
Sorry, I missed the updated patch somehow.
I'll apply it ASAP.
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] vmcore-dmesg: Do not write beyond end of allocated buffer
2012-07-18 13:33 ` Vivek Goyal
2012-07-23 14:35 ` Vivek Goyal
@ 2012-07-24 0:34 ` Simon Horman
1 sibling, 0 replies; 6+ messages in thread
From: Simon Horman @ 2012-07-24 0:34 UTC (permalink / raw)
To: Vivek Goyal; +Cc: Kexec Mailing List, Eric W. Biederman
On Wed, Jul 18, 2012 at 09:33:51AM -0400, Vivek Goyal wrote:
> On Wed, Jul 18, 2012 at 07:40:32AM +0900, Simon Horman wrote:
> > On Tue, Jul 17, 2012 at 11:23:00AM -0400, Vivek Goyal wrote:
> > > scan_vmcoreinfo() currently assumes that every line in vmcoreinfo note ends
> > > with \n and overwrites new line character with \0. But last entry in note,
> > > CRASHTIME= does not end with \n and this leads to corrupting memory as we
> > > write beyond end of buffer.
> > >
> > > Normally things were fine but when I added some fields to vmcoreinfo, this
> > > bug started showing and vmcore-dmesg started crashing.
> > >
> > > I am planning to send a patch to fix this in kernel but it might be good
> > > idea to handle this case in user space too so that vmcore-dmesg works
> > > fine with cores of older kernels.
> >
> > Good plan.
> >
> > > Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
> > > ---
> > > vmcore-dmesg/vmcore-dmesg.c | 27 ++++++++++++++++++++++++++-
> > > 1 file changed, 26 insertions(+), 1 deletion(-)
> > >
> > > Index: kexec-tools/vmcore-dmesg/vmcore-dmesg.c
> > > ===================================================================
> > > --- kexec-tools.orig/vmcore-dmesg/vmcore-dmesg.c 2012-07-19 01:54:02.700700235 -0400
> > > +++ kexec-tools/vmcore-dmesg/vmcore-dmesg.c 2012-07-19 01:55:08.232702248 -0400
> > > @@ -14,6 +14,7 @@
> > > #include <sys/stat.h>
> > > #include <fcntl.h>
> > > #include <elf.h>
> > > +#include <stdbool.h>
> > >
> > > /* The 32bit and 64bit note headers make it clear we don't care */
> > > typedef Elf32_Nhdr Elf_Nhdr;
> > > @@ -220,6 +221,9 @@ static void scan_vmcoreinfo(char *start,
> > > {
> > > char *last = start + size - 1;
> > > char *pos, *eol;
> > > + char temp_buf[1024];
> > > + bool last_line = false;
> >
> > Is there a chance of over-running temp_buf?
> >
> > I would be more comfortable if there was a check below to
> > ensure that len can never be greater than sizeof(temp_buf).
>
> Hi Simon,
>
> Agreed. Making sure temp_buf does not overflow is a good idea. Here is
> the udpated patch.
Thanks, applied.
_______________________________________________
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http://lists.infradead.org/mailman/listinfo/kexec
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2012-07-24 0:34 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2012-07-17 15:23 [PATCH] vmcore-dmesg: Do not write beyond end of allocated buffer Vivek Goyal
2012-07-17 22:40 ` Simon Horman
2012-07-18 13:33 ` Vivek Goyal
2012-07-23 14:35 ` Vivek Goyal
2012-07-23 23:08 ` Simon Horman
2012-07-24 0:34 ` Simon Horman
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