aboutsummaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorEric Andersen <andersen@codepoet.org>2002-06-04 13:28:43 +0000
committerEric Andersen <andersen@codepoet.org>2002-06-04 13:28:43 +0000
commitc06391be0d468eba7944f150636ba879487d43ca (patch)
treeba42036eb656c1e05711fc08e3eccd6a42089136
parent3b79370a7ddf749f1a475b10b017170c644d283b (diff)
downloadbusybox-c06391be0d468eba7944f150636ba879487d43ca.tar.gz
Avoid stack munching stdio implementations.
-Erik
-rw-r--r--modutils/modprobe.c175
1 files changed, 100 insertions, 75 deletions
diff --git a/modutils/modprobe.c b/modutils/modprobe.c
index 6a3e06df4..a72028fa2 100644
--- a/modutils/modprobe.c
+++ b/modutils/modprobe.c
@@ -9,13 +9,13 @@
*/
#include <sys/utsname.h>
-#include <stdio.h>
#include <getopt.h>
#include <stdlib.h>
#include <unistd.h>
#include <syslog.h>
#include <string.h>
#include <ctype.h>
+#include <fcntl.h>
#include "busybox.h"
@@ -46,11 +46,11 @@ static int autoclean, show_only, quiet, do_syslog, verbose;
static struct dep_t *build_dep ( void )
{
+ int fd, n;
struct utsname un;
- FILE *f;
struct dep_t *first = 0;
struct dep_t *current = 0;
- char buffer [4096];
+ char buffer[256];
char *filename = buffer;
int continuation_line = 0;
@@ -58,21 +58,35 @@ static struct dep_t *build_dep ( void )
return 0;
// check for buffer overflow in following code
- if ( xstrlen ( un. release ) > ( sizeof( buffer ) - 64 ))
+ if ( xstrlen ( un.release ) > ( sizeof( buffer ) - 64 )) {
return 0;
+ }
strcpy ( filename, "/lib/modules/" );
- strcat ( filename, un. release );
+ strcat ( filename, un.release );
strcat ( filename, "/modules.dep" );
- f = fopen ( filename, "r" );
- if ( !f )
+ if ((fd = open ( filename, O_RDONLY )) < 0)
return 0;
-
- while ( fgets ( buffer, sizeof( buffer), f )) {
- int l = xstrlen ( buffer );
+
+ while ( (n = read(fd, buffer, 255)) > 0) {
+ int l;
char *p = 0;
-
+
+ /* Jump through hoops to simulate how fgets() grabs just one line at a
+ * time... Don't use any stdio since modprobe gets called from a kernel
+ * thread and stdio junk can overflow the limited stack... */
+ p = strchr ( buffer, '\n' );
+ if (p) {
+ off_t offset;
+ /* Get the current file descriptor offset */
+ offset = lseek(fd, 0L, SEEK_CUR);
+ /* Set the file descriptor offset to right after the \n */
+ lseek(fd, offset-n+p-buffer+1, SEEK_SET);
+ *(p+1)='\0';
+ }
+
+ l = xstrlen ( buffer );
while ( isspace ( buffer [l-1] )) {
buffer [l-1] = 0;
l--;
@@ -105,10 +119,10 @@ static struct dep_t *build_dep ( void )
mod = xstrndup ( mods, col - mods - ext );
if ( !current ) {
- first = current = (struct dep_t *) malloc ( sizeof ( struct dep_t ));
+ first = current = (struct dep_t *) xmalloc ( sizeof ( struct dep_t ));
}
else {
- current-> m_next = (struct dep_t *) malloc ( sizeof ( struct dep_t ));
+ current-> m_next = (struct dep_t *) xmalloc ( sizeof ( struct dep_t ));
current = current-> m_next;
}
current-> m_module = mod;
@@ -164,79 +178,90 @@ static struct dep_t *build_dep ( void )
else
continuation_line = 0;
}
- fclose ( f );
+ close ( fd );
// alias parsing is not 100% correct (no correct handling of continuation lines within an alias) !
- f = fopen ( "/etc/modules.conf", "r" );
- if ( !f )
- f = fopen ( "/etc/conf.modules", "r" );
- if ( f ) {
- continuation_line = 0;
+ if ((fd = open ( "/etc/modules.conf", O_RDONLY )) < 0)
+ if ((fd = open ( "/etc/conf.modules", O_RDONLY )) < 0)
+ return first;
- while ( fgets ( buffer, sizeof( buffer), f )) {
- int l;
- char *p;
-
- p = strchr ( buffer, '#' );
- if ( p )
- *p = 0;
-
- l = xstrlen ( buffer );
+ continuation_line = 0;
+ while ( read(fd, buffer, 255) > 0) {
+ int l;
+ char *p;
- while ( l && isspace ( buffer [l-1] )) {
- buffer [l-1] = 0;
- l--;
- }
-
- if ( l == 0 ) {
- continuation_line = 0;
- continue;
- }
+ /* Jump through hoops to simulate how fgets() grabs just one line at a
+ * time... Don't use any stdio since modprobe gets called from a kernel
+ * thread and stdio junk can overflow the limited stack... */
+ p = strchr ( buffer, '\n' );
+ if (p) {
+ off_t offset;
+ /* Get the current file descriptor offset */
+ offset = lseek(fd, 0L, SEEK_CUR);
+ /* Set the file descriptor offset to right after the \n */
+ lseek(fd, offset-n+p-buffer+1, SEEK_SET);
+ *(p+1)='\0';
+ }
+
+ p = strchr ( buffer, '#' );
+ if ( p )
+ *p = 0;
- if ( !continuation_line ) {
- if (( strncmp ( buffer, "alias", 5 ) == 0 ) && isspace ( buffer [5] )) {
- char *alias, *mod;
+ l = xstrlen ( buffer );
+
+ while ( l && isspace ( buffer [l-1] )) {
+ buffer [l-1] = 0;
+ l--;
+ }
+
+ if ( l == 0 ) {
+ continuation_line = 0;
+ continue;
+ }
+
+ if ( !continuation_line ) {
+ if (( strncmp ( buffer, "alias", 5 ) == 0 ) && isspace ( buffer [5] )) {
+ char *alias, *mod;
- alias = buffer + 6;
-
- while ( isspace ( *alias ))
- alias++;
- mod = alias;
- while ( !isspace ( *mod ))
- mod++;
- *mod = 0;
+ alias = buffer + 6;
+
+ while ( isspace ( *alias ))
+ alias++;
+ mod = alias;
+ while ( !isspace ( *mod ))
+ mod++;
+ *mod = 0;
+ mod++;
+ while ( isspace ( *mod ))
mod++;
- while ( isspace ( *mod ))
- mod++;
-
+
// fprintf ( stderr, "ALIAS: '%s' -> '%s'\n", alias, mod );
-
- if ( !current ) {
- first = current = (struct dep_t *) malloc ( sizeof ( struct dep_t ));
- }
- else {
- current-> m_next = (struct dep_t *) malloc ( sizeof ( struct dep_t ));
- current = current-> m_next;
- }
- current-> m_module = xstrdup ( alias );
- current-> m_isalias = 1;
-
- if (( strcmp ( alias, "off" ) == 0 ) || ( strcmp ( alias, "null" ) == 0 )) {
- current-> m_depcnt = 0;
- current-> m_deparr = 0;
- }
- else {
- current-> m_depcnt = 1;
- current-> m_deparr = xmalloc ( 1 * sizeof( char * ));
- current-> m_deparr[0] = xstrdup ( mod );
- }
- current-> m_next = 0;
- }
- }
+
+ if ( !current ) {
+ first = current = (struct dep_t *) xmalloc ( sizeof ( struct dep_t ));
+ }
+ else {
+ current-> m_next = (struct dep_t *) xmalloc ( sizeof ( struct dep_t ));
+ current = current-> m_next;
+ }
+ current-> m_module = xstrdup ( alias );
+ current-> m_isalias = 1;
+
+ if (( strcmp ( alias, "off" ) == 0 ) || ( strcmp ( alias, "null" ) == 0 )) {
+ current-> m_depcnt = 0;
+ current-> m_deparr = 0;
+ }
+ else {
+ current-> m_depcnt = 1;
+ current-> m_deparr = xmalloc ( 1 * sizeof( char * ));
+ current-> m_deparr[0] = xstrdup ( mod );
+ }
+ current-> m_next = 0;
+ }
}
- fclose ( f );
}
+ close ( fd );
return first;
}