diff mbox

[dpdk-dev] pmdinfogen: fix resource leak of FILE object

Message ID 20180202120058.243184-1-bruce.richardson@intel.com (mailing list archive)
State Accepted, archived
Delegated to: Thomas Monjalon
Headers

Checks

Context Check Description
ci/checkpatch success coding style OK
ci/Intel-compilation success Compilation OK

Commit Message

Bruce Richardson Feb. 2, 2018, noon UTC 
  Coverity flags an issue where the resources used by the FILE object for
the temporary input file are leaked. This is a very minor issue, but is
easily fixed, while also avoiding later problems where we try to close
an invalid file descriptor in the failure case.

The fix is to use "dup()" to get a new file descriptor number rather than
using the value directly from fileno. This allows us to close the file
opened with tmpfile() within in scope block, while allowing the duplicate
to pass to the outer block and be closed when the function terminates.

As a side-effect I/O in the function is therefore changed from using stdio
fread/fwrite to read/write system calls.

Coverity issue: 260399
Fixes: 0d68533617e3 ("pmdinfogen: allow using stdin and stdout")

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
---
 buildtools/pmdinfogen/pmdinfogen.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

Comments

Neil Horman Feb. 2, 2018, 12:44 p.m. UTC | #1 
On Fri, Feb 02, 2018 at 12:00:58PM +0000, Bruce Richardson wrote:
> Coverity flags an issue where the resources used by the FILE object for
> the temporary input file are leaked. This is a very minor issue, but is
> easily fixed, while also avoiding later problems where we try to close
> an invalid file descriptor in the failure case.
> 
> The fix is to use "dup()" to get a new file descriptor number rather than
> using the value directly from fileno. This allows us to close the file
> opened with tmpfile() within in scope block, while allowing the duplicate
> to pass to the outer block and be closed when the function terminates.
> 
> As a side-effect I/O in the function is therefore changed from using stdio
> fread/fwrite to read/write system calls.
> 
> Coverity issue: 260399
> Fixes: 0d68533617e3 ("pmdinfogen: allow using stdin and stdout")
> 
> Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
> ---
>  buildtools/pmdinfogen/pmdinfogen.c | 16 ++++++++++------
>  1 file changed, 10 insertions(+), 6 deletions(-)
> 
> diff --git a/buildtools/pmdinfogen/pmdinfogen.c b/buildtools/pmdinfogen/pmdinfogen.c
> index 45b267346..0f35ca46b 100644
> --- a/buildtools/pmdinfogen/pmdinfogen.c
> +++ b/buildtools/pmdinfogen/pmdinfogen.c
> @@ -50,20 +50,24 @@ static void *grab_file(const char *filename, unsigned long *size)
>  		/* from stdin, use a temporary file to mmap */
>  		FILE *infile;
>  		char buffer[1024];
> -		size_t n;
> +		int n;
>  
>  		infile = tmpfile();
>  		if (infile == NULL) {
>  			perror("tmpfile");
>  			return NULL;
>  		}
> -		while (!feof(stdin)) {
> -			n = fread(buffer, 1, sizeof(buffer), stdin);
> -			if (fwrite(buffer, 1, n, infile) != n)
> +		fd = dup(fileno(infile));
> +		fclose(infile);
> +		if (fd < 0)
> +			return NULL;
> +
> +		n = read(STDIN_FILENO, buffer, sizeof(buffer));
> +		while (n > 0) {
> +			if (write(fd, buffer, n) != n)
>  				goto failed;
> +			n = read(STDIN_FILENO, buffer, sizeof(buffer));
>  		}
> -		fflush(infile);
> -		fd = fileno(infile);
>  	}
>  
>  	if (fstat(fd, &st))
> -- 
> 2.14.3
> 
> 

Wouldn't it be just as good, and easier to check fd for == -1 as a condition of
calling close?

like 
failed:
	if (fd >= 0)
		close(fd);
Bruce Richardson Feb. 2, 2018, 3:47 p.m. UTC | #2 
On Fri, Feb 02, 2018 at 07:44:39AM -0500, Neil Horman wrote:
> On Fri, Feb 02, 2018 at 12:00:58PM +0000, Bruce Richardson wrote:
> > Coverity flags an issue where the resources used by the FILE object for
> > the temporary input file are leaked. This is a very minor issue, but is
> > easily fixed, while also avoiding later problems where we try to close
> > an invalid file descriptor in the failure case.
> > 
> > The fix is to use "dup()" to get a new file descriptor number rather than
> > using the value directly from fileno. This allows us to close the file
> > opened with tmpfile() within in scope block, while allowing the duplicate
> > to pass to the outer block and be closed when the function terminates.
> > 
> > As a side-effect I/O in the function is therefore changed from using stdio
> > fread/fwrite to read/write system calls.
> > 
> > Coverity issue: 260399
> > Fixes: 0d68533617e3 ("pmdinfogen: allow using stdin and stdout")
> > 
> > Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
> > ---
> >  buildtools/pmdinfogen/pmdinfogen.c | 16 ++++++++++------
> >  1 file changed, 10 insertions(+), 6 deletions(-)
> > 
> > diff --git a/buildtools/pmdinfogen/pmdinfogen.c b/buildtools/pmdinfogen/pmdinfogen.c
> > index 45b267346..0f35ca46b 100644
> > --- a/buildtools/pmdinfogen/pmdinfogen.c
> > +++ b/buildtools/pmdinfogen/pmdinfogen.c
> > @@ -50,20 +50,24 @@ static void *grab_file(const char *filename, unsigned long *size)
> >  		/* from stdin, use a temporary file to mmap */
> >  		FILE *infile;
> >  		char buffer[1024];
> > -		size_t n;
> > +		int n;
> >  
> >  		infile = tmpfile();
> >  		if (infile == NULL) {
> >  			perror("tmpfile");
> >  			return NULL;
> >  		}
> > -		while (!feof(stdin)) {
> > -			n = fread(buffer, 1, sizeof(buffer), stdin);
> > -			if (fwrite(buffer, 1, n, infile) != n)
> > +		fd = dup(fileno(infile));
> > +		fclose(infile);
> > +		if (fd < 0)
> > +			return NULL;
> > +
> > +		n = read(STDIN_FILENO, buffer, sizeof(buffer));
> > +		while (n > 0) {
> > +			if (write(fd, buffer, n) != n)
> >  				goto failed;
> > +			n = read(STDIN_FILENO, buffer, sizeof(buffer));
> >  		}
> > -		fflush(infile);
> > -		fd = fileno(infile);
> >  	}
> >  
> >  	if (fstat(fd, &st))
> > -- 
> > 2.14.3
> > 
> > 
> 
> Wouldn't it be just as good, and easier to check fd for == -1 as a condition of
> calling close?
> 
> like 
> failed:
> 	if (fd >= 0)
> 		close(fd);
> 
That would fix the problem of calling goto failed with fd set to -1, but
would not fix the resource issue that coverity was complaining about. We
were allocating a stdio FILE object, then taking just the fileno of it
and letting the file number go out of scope. This cleans this that up,
so that we just use file numbers and properly close the FILE * once it's
outlived its usefulness.

BTW: I did investigate using open and O_TMPFILE in place of tmpfile()
call, but while it would work great on Linux, it's not available
elsewhere, so tmpfile looks the best option.

Regards,
/Bruce
Bruce Richardson Feb. 2, 2018, 3:51 p.m. UTC | #3 
On Fri, Feb 02, 2018 at 03:47:43PM +0000, Bruce Richardson wrote:
> On Fri, Feb 02, 2018 at 07:44:39AM -0500, Neil Horman wrote:
> > On Fri, Feb 02, 2018 at 12:00:58PM +0000, Bruce Richardson wrote:
> > > Coverity flags an issue where the resources used by the FILE object for
> > > the temporary input file are leaked. This is a very minor issue, but is
> > > easily fixed, while also avoiding later problems where we try to close
> > > an invalid file descriptor in the failure case.
> > > 
> > > The fix is to use "dup()" to get a new file descriptor number rather than
> > > using the value directly from fileno. This allows us to close the file
> > > opened with tmpfile() within in scope block, while allowing the duplicate
> > > to pass to the outer block and be closed when the function terminates.
> > > 
> > > As a side-effect I/O in the function is therefore changed from using stdio
> > > fread/fwrite to read/write system calls.
> > > 
> > > Coverity issue: 260399
> > > Fixes: 0d68533617e3 ("pmdinfogen: allow using stdin and stdout")
> > > 
> > > Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
> > > ---
> > >  buildtools/pmdinfogen/pmdinfogen.c | 16 ++++++++++------
> > >  1 file changed, 10 insertions(+), 6 deletions(-)
> > > 
> > > diff --git a/buildtools/pmdinfogen/pmdinfogen.c b/buildtools/pmdinfogen/pmdinfogen.c
> > > index 45b267346..0f35ca46b 100644
> > > --- a/buildtools/pmdinfogen/pmdinfogen.c
> > > +++ b/buildtools/pmdinfogen/pmdinfogen.c
> > > @@ -50,20 +50,24 @@ static void *grab_file(const char *filename, unsigned long *size)
> > >  		/* from stdin, use a temporary file to mmap */
> > >  		FILE *infile;
> > >  		char buffer[1024];
> > > -		size_t n;
> > > +		int n;
> > >  
> > >  		infile = tmpfile();
> > >  		if (infile == NULL) {
> > >  			perror("tmpfile");
> > >  			return NULL;
> > >  		}
> > > -		while (!feof(stdin)) {
> > > -			n = fread(buffer, 1, sizeof(buffer), stdin);
> > > -			if (fwrite(buffer, 1, n, infile) != n)
> > > +		fd = dup(fileno(infile));
> > > +		fclose(infile);
> > > +		if (fd < 0)
> > > +			return NULL;
> > > +
> > > +		n = read(STDIN_FILENO, buffer, sizeof(buffer));
> > > +		while (n > 0) {
> > > +			if (write(fd, buffer, n) != n)
> > >  				goto failed;
> > > +			n = read(STDIN_FILENO, buffer, sizeof(buffer));
> > >  		}
> > > -		fflush(infile);
> > > -		fd = fileno(infile);
> > >  	}
> > >  
> > >  	if (fstat(fd, &st))
> > > -- 
> > > 2.14.3
> > > 
> > > 
> > 
> > Wouldn't it be just as good, and easier to check fd for == -1 as a condition of
> > calling close?
> > 
> > like 
> > failed:
> > 	if (fd >= 0)
> > 		close(fd);
> > 
> That would fix the problem of calling goto failed with fd set to -1, but
> would not fix the resource issue that coverity was complaining about. We
> were allocating a stdio FILE object, then taking just the fileno of it
> and letting the file number go out of scope. This cleans this that up,
s/file number/FILE object ptr/

> so that we just use file numbers and properly close the FILE * once it's
> outlived its usefulness.
> 
> BTW: I did investigate using open and O_TMPFILE in place of tmpfile()
> call, but while it would work great on Linux, it's not available
> elsewhere, so tmpfile looks the best option.
> 
> Regards,
> /Bruce
Neil Horman Feb. 2, 2018, 6:47 p.m. UTC | #4 
On Fri, Feb 02, 2018 at 03:51:12PM +0000, Bruce Richardson wrote:
> On Fri, Feb 02, 2018 at 03:47:43PM +0000, Bruce Richardson wrote:
> > On Fri, Feb 02, 2018 at 07:44:39AM -0500, Neil Horman wrote:
> > > On Fri, Feb 02, 2018 at 12:00:58PM +0000, Bruce Richardson wrote:
> > > > Coverity flags an issue where the resources used by the FILE object for
> > > > the temporary input file are leaked. This is a very minor issue, but is
> > > > easily fixed, while also avoiding later problems where we try to close
> > > > an invalid file descriptor in the failure case.
> > > > 
> > > > The fix is to use "dup()" to get a new file descriptor number rather than
> > > > using the value directly from fileno. This allows us to close the file
> > > > opened with tmpfile() within in scope block, while allowing the duplicate
> > > > to pass to the outer block and be closed when the function terminates.
> > > > 
> > > > As a side-effect I/O in the function is therefore changed from using stdio
> > > > fread/fwrite to read/write system calls.
> > > > 
> > > > Coverity issue: 260399
> > > > Fixes: 0d68533617e3 ("pmdinfogen: allow using stdin and stdout")
> > > > 
> > > > Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
> > > > ---
> > > >  buildtools/pmdinfogen/pmdinfogen.c | 16 ++++++++++------
> > > >  1 file changed, 10 insertions(+), 6 deletions(-)
> > > > 
> > > > diff --git a/buildtools/pmdinfogen/pmdinfogen.c b/buildtools/pmdinfogen/pmdinfogen.c
> > > > index 45b267346..0f35ca46b 100644
> > > > --- a/buildtools/pmdinfogen/pmdinfogen.c
> > > > +++ b/buildtools/pmdinfogen/pmdinfogen.c
> > > > @@ -50,20 +50,24 @@ static void *grab_file(const char *filename, unsigned long *size)
> > > >  		/* from stdin, use a temporary file to mmap */
> > > >  		FILE *infile;
> > > >  		char buffer[1024];
> > > > -		size_t n;
> > > > +		int n;
> > > >  
> > > >  		infile = tmpfile();
> > > >  		if (infile == NULL) {
> > > >  			perror("tmpfile");
> > > >  			return NULL;
> > > >  		}
> > > > -		while (!feof(stdin)) {
> > > > -			n = fread(buffer, 1, sizeof(buffer), stdin);
> > > > -			if (fwrite(buffer, 1, n, infile) != n)
> > > > +		fd = dup(fileno(infile));
> > > > +		fclose(infile);
> > > > +		if (fd < 0)
> > > > +			return NULL;
> > > > +
> > > > +		n = read(STDIN_FILENO, buffer, sizeof(buffer));
> > > > +		while (n > 0) {
> > > > +			if (write(fd, buffer, n) != n)
> > > >  				goto failed;
> > > > +			n = read(STDIN_FILENO, buffer, sizeof(buffer));
> > > >  		}
> > > > -		fflush(infile);
> > > > -		fd = fileno(infile);
> > > >  	}
> > > >  
> > > >  	if (fstat(fd, &st))
> > > > -- 
> > > > 2.14.3
> > > > 
> > > > 
> > > 
> > > Wouldn't it be just as good, and easier to check fd for == -1 as a condition of
> > > calling close?
> > > 
> > > like 
> > > failed:
> > > 	if (fd >= 0)
> > > 		close(fd);
> > > 
> > That would fix the problem of calling goto failed with fd set to -1, but
> > would not fix the resource issue that coverity was complaining about. We
> > were allocating a stdio FILE object, then taking just the fileno of it
> > and letting the file number go out of scope. This cleans this that up,
> s/file number/FILE object ptr/
> 
Yeah, Ok, I can see that, though I still think its a bit of a false positive,
since the definition of tmpfile says it will automatically unlink the file on
process exit.  No matter though, what you have is an improvement regardless.

> > so that we just use file numbers and properly close the FILE * once it's
> > outlived its usefulness.
> > 
> > BTW: I did investigate using open and O_TMPFILE in place of tmpfile()
> > call, but while it would work great on Linux, it's not available
> > elsewhere, so tmpfile looks the best option.
> > 
yeah, thats both OS and filesystem specific, I wouldn't trust it too much.

Acked-by: Neil Horman <nhorman@tuxdriver.com>

> > Regards,
> > /Bruce
>
Thomas Monjalon Feb. 6, 2018, 12:16 a.m. UTC | #5 
02/02/2018 19:47, Neil Horman:
> On Fri, Feb 02, 2018 at 03:51:12PM +0000, Bruce Richardson wrote:
> > On Fri, Feb 02, 2018 at 03:47:43PM +0000, Bruce Richardson wrote:
> > > On Fri, Feb 02, 2018 at 07:44:39AM -0500, Neil Horman wrote:
> > > > On Fri, Feb 02, 2018 at 12:00:58PM +0000, Bruce Richardson wrote:
> > > > > Coverity flags an issue where the resources used by the FILE object for
> > > > > the temporary input file are leaked. This is a very minor issue, but is
> > > > > easily fixed, while also avoiding later problems where we try to close
> > > > > an invalid file descriptor in the failure case.
> > > > > 
> > > > > The fix is to use "dup()" to get a new file descriptor number rather than
> > > > > using the value directly from fileno. This allows us to close the file
> > > > > opened with tmpfile() within in scope block, while allowing the duplicate
> > > > > to pass to the outer block and be closed when the function terminates.
> > > > > 
> > > > > As a side-effect I/O in the function is therefore changed from using stdio
> > > > > fread/fwrite to read/write system calls.
> > > > > 
> > > > > Coverity issue: 260399
> > > > > Fixes: 0d68533617e3 ("pmdinfogen: allow using stdin and stdout")
> > > > > 
> > > > > Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
[...]
> Acked-by: Neil Horman <nhorman@tuxdriver.com>

Applied, thanks
diff mbox

Patch

diff --git a/buildtools/pmdinfogen/pmdinfogen.c b/buildtools/pmdinfogen/pmdinfogen.c
index 45b267346..0f35ca46b 100644
--- a/buildtools/pmdinfogen/pmdinfogen.c
+++ b/buildtools/pmdinfogen/pmdinfogen.c
@@ -50,20 +50,24 @@  static void *grab_file(const char *filename, unsigned long *size)
 		/* from stdin, use a temporary file to mmap */
 		FILE *infile;
 		char buffer[1024];
-		size_t n;
+		int n;
 
 		infile = tmpfile();
 		if (infile == NULL) {
 			perror("tmpfile");
 			return NULL;
 		}
-		while (!feof(stdin)) {
-			n = fread(buffer, 1, sizeof(buffer), stdin);
-			if (fwrite(buffer, 1, n, infile) != n)
+		fd = dup(fileno(infile));
+		fclose(infile);
+		if (fd < 0)
+			return NULL;
+
+		n = read(STDIN_FILENO, buffer, sizeof(buffer));
+		while (n > 0) {
+			if (write(fd, buffer, n) != n)
 				goto failed;
+			n = read(STDIN_FILENO, buffer, sizeof(buffer));
 		}
-		fflush(infile);
-		fd = fileno(infile);
 	}
 
 	if (fstat(fd, &st))