[PATCH 0/2] ipcs: more robust and compatible /proc parsing

[PATCH 0/2] ipcs: more robust and compatible /proc parsing

[Ruediger Meier]

From: Ruediger Meier <ruediger.meier@ga-group.nl>

If this looks ok for shm then we could also add similar patches for
sem and msg.

Ruediger Meier (2):
  ipcs: make sure to parse whole lines for shm_data
  ipcs: --shmems, upward/backward compatibility

 sys-utils/ipcutils.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

-- 
1.8.4.5

[PATCH 1/2] ipcs: make sure to parse whole lines for shm_data

[Ruediger Meier]

From: Ruediger Meier <ruediger.meier@ga-group.nl>

We want to parse 16 columns _per_row_ without mixing them up. The
existing code is unsafe for more or less columns and could even
run into endless loops. This patch assures that we parse row-wise
and really skip lines with columns != 16.

Probably somehow we could have also done this with fscanf() only.
Using fgets() additionally makes the code more easy to read and
to improve later.

Signed-off-by: Ruediger Meier <ruediger.meier@ga-group.nl>
---
 sys-utils/ipcutils.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/sys-utils/ipcutils.c b/sys-utils/ipcutils.c
index 400f00c..c763cde 100644
--- a/sys-utils/ipcutils.c
+++ b/sys-utils/ipcutils.c
@@ -99,6 +99,7 @@ int ipc_shm_get_info(int id, struct shm_data **shmds)
 {
 	FILE *f;
 	int i = 0, maxid;
+	char buf[BUFSIZ];
 	struct shm_data *p;
 	struct shmid_ds dummy;
 
@@ -111,8 +112,8 @@ int ipc_shm_get_info(int id, struct shm_data **shmds)
 
 	while (fgetc(f) != '\n');		/* skip header */
 
-	while (feof(f) == 0) {
-		if (fscanf(f,
+	while (fgets(buf, sizeof(buf), f) != NULL) {
+		if (sscanf(buf,
 			  "%d %d  %o %"SCNu64 " %u %u  "
 			  "%"SCNu64 " %u %u %u %u %"SCNi64 " %"SCNi64 " %"SCNi64
 			  " %"SCNu64 " %"SCNu64 "\n",
@@ -132,7 +133,7 @@ int ipc_shm_get_info(int id, struct shm_data **shmds)
 			   &p->shm_ctim,
 			   &p->shm_rss,
 			   &p->shm_swp) != 16)
-			continue;
+			continue; /* ivalid line, skipped */
 
 		if (id > -1) {
 			/* ID specified */
-- 
1.8.4.5

[PATCH 2/2] ipcs: --shmems, upward/backward compatibility

[Ruediger Meier]

From: Ruediger Meier <ruediger.meier@ga-group.nl>

Re-add backward compatibility which got lost in 058e8154.
Initializing unknown struct members to 0xdead is similar to
the fallback.

For upward compatibility ignore columns > 16 but not the whole
line (in case the kernel would add more columns in future).

Reported-by: Benno Schulenberg <bensberg@justemail.net>
Signed-off-by: Ruediger Meier <ruediger.meier@ga-group.nl>
---
 sys-utils/ipcutils.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/sys-utils/ipcutils.c b/sys-utils/ipcutils.c
index c763cde..349e855 100644
--- a/sys-utils/ipcutils.c
+++ b/sys-utils/ipcutils.c
@@ -113,6 +113,9 @@ int ipc_shm_get_info(int id, struct shm_data **shmds)
 	while (fgetc(f) != '\n');		/* skip header */
 
 	while (fgets(buf, sizeof(buf), f) != NULL) {
+		/* scan for the first 14-16 columns (e.g. Linux 2.6.32 has 14) */
+		p->shm_rss = 0xdead;
+		p->shm_swp = 0xdead;
 		if (sscanf(buf,
 			  "%d %d  %o %"SCNu64 " %u %u  "
 			  "%"SCNu64 " %u %u %u %u %"SCNi64 " %"SCNi64 " %"SCNi64
@@ -132,7 +135,7 @@ int ipc_shm_get_info(int id, struct shm_data **shmds)
 			   &p->shm_dtim,
 			   &p->shm_ctim,
 			   &p->shm_rss,
-			   &p->shm_swp) != 16)
+			   &p->shm_swp) < 14)
 			continue; /* ivalid line, skipped */
 
 		if (id > -1) {
-- 
1.8.4.5

Re: [PATCH 0/2] ipcs: more robust and compatible /proc parsing

[Karel Zak]

On Fri, Mar 18, 2016 at 12:49:16PM +0100, Ruediger Meier wrote:
> From: Ruediger Meier <ruediger.meier@ga-group.nl>
> 
> If this looks ok for shm then we could also add similar patches for
> sem and msg.

Seems good, I'll wait for complete set of the patches, ok?

    Karel

-- 
 Karel Zak  <kzak@redhat.com>
 http://karelzak.blogspot.com

Re: [PATCH 0/2] ipcs: more robust and compatible /proc parsing

[Ruediger Meier]

On Friday 18 March 2016, Karel Zak wrote:
> On Fri, Mar 18, 2016 at 12:49:16PM +0100, Ruediger Meier wrote:
> > From: Ruediger Meier <ruediger.meier@ga-group.nl>
> >
> > If this looks ok for shm then we could also add similar patches for
> > sem and msg.
>
> Seems good, I'll wait for complete set of the patches, ok?

For msg and sem we don't have compatibility problems or bugs in real 
life but only these _potential_ fscanf issues. Not so important for 
2.28.

I would like to do that later in a project wide scanf review but without 
hurry.

cu,
Rudi 

Re: [PATCH 0/2] ipcs: more robust and compatible /proc parsing

[Karel Zak]

On Fri, Mar 18, 2016 at 03:03:32PM +0100, Ruediger Meier wrote:
> On Friday 18 March 2016, Karel Zak wrote:
> > On Fri, Mar 18, 2016 at 12:49:16PM +0100, Ruediger Meier wrote:
> > > From: Ruediger Meier <ruediger.meier@ga-group.nl>
> > >
> > > If this looks ok for shm then we could also add similar patches for
> > > sem and msg.
> >
> > Seems good, I'll wait for complete set of the patches, ok?
> 
> For msg and sem we don't have compatibility problems or bugs in real 
> life but only these _potential_ fscanf issues. Not so important for 
> 2.28.
> 
> I would like to do that later in a project wide scanf review but without 
> hurry.

 OK, Applied, thanks.

    Karel

-- 
 Karel Zak  <kzak@redhat.com>
 http://karelzak.blogspot.com