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libmount: don't use sscanf() for mountinfo parsing 

Addresses: https://github.com/karelzak/util-linux/issues/780
Signed-off-by: Karel Zak <kzak@redhat.com>
This commit is contained in:
Karel Zak 2019-04-08 13:33:04 +02:00
parent 36fcefa651
commit 86673b3a46
2 changed files with 113 additions and 91 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/pathnames.h
View File

@ -15,7 +15,7 @@
#endif
/* used by kernel in /proc (e.g. /proc/swaps) for deleted files */
#define PATH_DELETED_SUFFIX "\\040(deleted)"
#define PATH_DELETED_SUFFIX " (deleted)"
#define PATH_DELETED_SUFFIX_SZ (sizeof(PATH_DELETED_SUFFIX) - 1)
/* DEFPATHs from <paths.h> don't include /usr/local */

202
libmount/src/tab_parse.c
View File

@ -47,8 +47,10 @@ static const char *next_number(const char *s, int *num, int *rc)
{
char *end = NULL;
if (!s || !*s)
return s;
assert(num);
assert(s);
assert(rc);
*rc = -EINVAL;
@ -70,6 +72,13 @@ static inline const char *skip_separator(const char *p)
return p;
}
static inline const char *skip_nonspearator(const char *p)
{
while (p && *p && !(*p == ' ' || *p == '\t'))
p++;
return p;
}
/*
* Parses one line from {fs,m}tab
*/
@ -82,7 +91,7 @@ static int mnt_parse_table_line(struct libmnt_fs *fs, const char *s)
/* (1) source */
p = unmangle(s, &s);
if (!p || (rc = __mnt_fs_set_source_ptr(fs, p))) {
if (!p || (rc = __mnt_fs_set_source_ptr(fs, p))) {
DBG(TAB, ul_debug("tab parse error: [source]"));
goto fail;
}
@ -153,29 +162,68 @@ fail:
*/
static int mnt_parse_mountinfo_line(struct libmnt_fs *fs, const char *s)
{
int rc, end = 0;
int rc = 0;
unsigned int maj, min;
char *fstype = NULL, *src = NULL;
const char *p;
char *p;
rc = sscanf(s, "%d " /* (1) id */
"%d " /* (2) parent */
"%u:%u " /* (3) maj:min */
UL_SCNsA" " /* (4) mountroot */
UL_SCNsA" " /* (5) target */
UL_SCNsA /* (6) vfs options (fs-independent) */
"%n", /* number of read bytes */
fs->flags |= MNT_FS_KERNEL;
&fs->id,
&fs->parent,
&maj, &min,
&fs->root,
&fs->target,
&fs->vfs_optstr,
&end);
/* (1) id */
s = next_number(s, &fs->id, &rc);
if (!s || !*s || rc) {
DBG(TAB, ul_debug("tab parse error: [id]"));
goto fail;
}
if (rc >= 7 && end > 0)
s += end;
s = skip_separator(s);
/* (2) parent */
s = next_number(s, &fs->parent, &rc);
if (!s || !*s || rc) {
DBG(TAB, ul_debug("tab parse error: [parent]"));
goto fail;
}
s = skip_separator(s);
/* (3) maj:min */
if (sscanf(s, "%u:%u", &maj, &min) != 2) {
DBG(TAB, ul_debug("tab parse error: [maj:min]"));
goto fail;
}
fs->devno = makedev(maj, min);
s = skip_nonspearator(s);
s = skip_separator(s);
/* (4) mountroot */
fs->root = unmangle(s, &s);
if (!fs->root) {
DBG(TAB, ul_debug("tab parse error: [mountroot]"));
goto fail;
}
s = skip_separator(s);
/* (5) target */
fs->target = unmangle(s, &s);
if (!fs->target) {
DBG(TAB, ul_debug("tab parse error: [target]"));
goto fail;
}
/* remove "\040(deleted)" suffix */
p = (char *) endswith(fs->target, PATH_DELETED_SUFFIX);
if (p && *p)
*p = '\0';
s = skip_separator(s);
/* (6) vfs options (fs-independent) */
fs->vfs_optstr = unmangle(s, &s);
if (!fs->vfs_optstr) {
DBG(TAB, ul_debug("tab parse error: [VFS options]"));
goto fail;
}
/* (7) optional fields, terminated by " - " */
p = strstr(s, " - ");
@ -185,82 +233,56 @@ static int mnt_parse_mountinfo_line(struct libmnt_fs *fs, const char *s)
}
if (p > s + 1)
fs->opt_fields = strndup(s + 1, p - s - 1);
s = p + 3;
end = 0;
rc += sscanf(s, UL_SCNsA"%n", /* (8) FS type */
s = skip_separator(p + 3);
&fstype,
&end);
if (rc >= 8 && end > 0)
s += end;
if (s[0] == ' ')
s++;
/* (9) source can unfortunately be an empty string "" and scanf does
* not work well with empty string. Test with:
* $ sudo mount -t tmpfs "" /tmp/bb
* $ mountpoint /tmp/bb
* */
if (s[0] == ' ') {
src = strdup("");
s++;
rc++;
rc += sscanf(s, UL_SCNsA, /* (10) fs options (fs specific) */
&fs->fs_optstr);
} else {
rc += sscanf(s, UL_SCNsA" " /* (9) source */
UL_SCNsA, /* (10) fs options (fs specific) */
&src,
&fs->fs_optstr);
/* (8) FS type */
p = unmangle(s, &s);
if (!p || (rc = __mnt_fs_set_fstype_ptr(fs, p))) {
DBG(TAB, ul_debug("tab parse error: [fstype]"));
goto fail;
}
if (rc >= 10) {
size_t sz;
fs->flags |= MNT_FS_KERNEL;
fs->devno = makedev(maj, min);
/* remove "\040(deleted)" suffix */
sz = strlen(fs->target);
if (sz > PATH_DELETED_SUFFIX_SZ) {
char *ptr = fs->target + (sz - PATH_DELETED_SUFFIX_SZ);
if (strcmp(ptr, PATH_DELETED_SUFFIX) == 0)
*ptr = '\0';
/* (9) source -- maybe empty string */
if (!s || !*s) {
DBG(TAB, ul_debug("tab parse error: [source]"));
goto fail;
} else if (*s == ' ' && *(s+1) == ' ') {
if ((rc = mnt_fs_set_source(fs, ""))) {
DBG(TAB, ul_debug("tab parse error: [empty source]"));
goto fail;
}
unmangle_string(fs->root);
unmangle_string(fs->target);
unmangle_string(fs->vfs_optstr);
unmangle_string(fstype);
unmangle_string(src);
unmangle_string(fs->fs_optstr);
rc = __mnt_fs_set_fstype_ptr(fs, fstype);
if (!rc) {
fstype = NULL;
rc = __mnt_fs_set_source_ptr(fs, src);
if (!rc)
src = NULL;
}
/* merge VFS and FS options to one string */
fs->optstr = mnt_fs_strdup_options(fs);
if (!fs->optstr)
rc = -ENOMEM;
} else {
DBG(TAB, ul_debug(
"mountinfo parse error [sscanf rc=%d]: '%s'", rc, s));
s = skip_separator(s);
p = unmangle(s, &s);
if (!p || (rc = __mnt_fs_set_source_ptr(fs, p))) {
DBG(TAB, ul_debug("tab parse error: [regular source]"));
goto fail;
}
}
s = skip_separator(s);
/* (10) fs options (fs specific) */
fs->fs_optstr = unmangle(s, &s);
if (!fs->fs_optstr) {
DBG(TAB, ul_debug("tab parse error: [FS options]"));
goto fail;
}
/* merge VFS and FS options to one string */
fs->optstr = mnt_fs_strdup_options(fs);
if (!fs->optstr) {
rc = -ENOMEM;
DBG(TAB, ul_debug("tab parse error: [merge VFS and FS options]"));
goto fail;
}
return 0;
fail:
if (rc == 0)
rc = -EINVAL;
}
free(fstype);
free(src);
DBG(TAB, ul_debug("tab parse error on: '%s' [rc=%d]", s, rc));
return rc;
}