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VFS: prevent buffer overflow

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If an FS returns faulty struct dirent data, VFS could overflow
a buffer that holds this data.
This commit is contained in:
Thomas Veerman 2012-07-17 08:47:51 +00:00
parent cbcdb838f1
commit 06f49fe167
1 changed files with 12 additions and 3 deletions
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15
servers/vfs/path.c
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@ -10,9 +10,11 @@
#include <minix/keymap.h>
#include <minix/const.h>
#include <minix/endpoint.h>
#include <stddef.h>
#include <unistd.h>
#include <assert.h>
#include <minix/vfsif.h>
#include <sys/param.h>
#include <sys/stat.h>
#include <sys/un.h>
#include <dirent.h>
@ -545,9 +547,11 @@ struct vnode *dirp;
struct vnode *entry;
char ename[NAME_MAX + 1];
{
#define DIR_ENTRIES 8
#define DIR_ENTRY_SIZE (sizeof(struct dirent) + NAME_MAX)
u64_t pos, new_pos;
int r, consumed, totalbytes;
char buf[(sizeof(struct dirent) + NAME_MAX) * 8];
int r, consumed, totalbytes, name_len;
char buf[DIR_ENTRY_SIZE * DIR_ENTRIES];
struct dirent *cur;
pos = make64(0, 0);
@ -569,9 +573,14 @@ char ename[NAME_MAX + 1];
do {
cur = (struct dirent *) (buf + consumed);
name_len = cur->d_reclen - offsetof(struct dirent, d_name) - 1;
if(cur->d_name + name_len >= &buf[DIR_ENTRIES * DIR_ENTRY_SIZE])
return(EINVAL); /* Rubbish in dir entry */
if (entry->v_inode_nr == cur->d_ino) {
/* found the entry we were looking for */
strlcpy(ename, cur->d_name, NAME_MAX+1);
strlcpy(ename, cur->d_name,
MIN(name_len + 1, NAME_MAX + 1));
ename[NAME_MAX] = '\0';
return(OK);
}