CVE-2014-9114 (published 2017-03-31T16:59Z)

Blkid in util-linux before 2.26rc-1 allows local users to execute arbitrary code.

Severity: HIGH
CVSS v2 base score: 7.2 (AV:L/AC:L/Au:N/C:C/I:C/A:C)
CVSS v3 base score: 7.8, HIGH (CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H)

Weakness information:
cwe_id: CWE-77
cwe_name: Improper Neutralization of Special Elements used in a Command ('Command Injection')
description: The product constructs all or part of a command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended command when it is sent to a downstream component.
extended_description: 
            Many protocols and products have their own custom command language. While OS or shell command strings are frequently discovered and targeted, developers may not realize that these other command languages might also be vulnerable to attacks.
         
         

Fix information:
repo_url: https://github.com/karelzak/util-linux
commit_details: repo_url: https://github.com/karelzak/util-linux
author: Karel Zak
author_date: 2014-11-27 13:39:35+01:00
msg: libblkid: care about unsafe chars in cache

The high-level libblkid API uses /run/blkid/blkid.tab cache to
store probing results. The cache format is

   <device NAME="value" ...>devname</device>

and unfortunately the cache code does not escape quotation marks:

   # mkfs.ext4 -L 'AAA"BBB'

   # cat /run/blkid/blkid.tab
   ...
   <device ... LABEL="AAA"BBB" ...>/dev/sdb1</device>

such string is later incorrectly parsed and blkid(8) returns
nonsenses. And for use-cases like

   # eval $(blkid -o export /dev/sdb1)

it's also insecure.

Note that mount, udevd and blkid -p are based on low-level libblkid
API, it bypass the cache and directly read data from the devices.

The current udevd upstream does not depend on blkid(8) output at all,
it's directly linked with the library and all unsafe chars are encoded by
\x<hex> notation.

   # mkfs.ext4 -L 'X"`/tmp/foo` "' /dev/sdb1
   # udevadm info --export-db | grep LABEL
   ...
   E: ID_FS_LABEL=X__/tmp/foo___
   E: ID_FS_LABEL_ENC=X\x22\x60\x2ftmp\x2ffoo\x60\x20\x22

Signed-off-by: Karel Zak <kzak@redhat.com>
repository: repo_url: https://github.com/karelzak/util-linux
repo_name: util-linux/util-linux
repo_language: C
owner: karelzak
file_changes: filename: read.c
change_type: ModificationType.MODIFY
diff: @@ -252,15 +252,30 @@ static int parse_token(char **name, char **value, char **cp)
 	*value = skip_over_blank(*value + 1);
 
 	if (**value == '"') {
-		end = strchr(*value + 1, '"');
-		if (!end) {
+		char *p = end = *value + 1;
+
+		/* convert 'foo\"bar'  to 'foo"bar' */
+		while (*p) {
+			if (*p == '\\') {
+				p++;
+				*end = *p;
+			} else {
+				*end = *p;
+				if (*p == '"')
+					break;
+			}
+			p++;
+			end++;
+		}
+
+		if (*end != '"') {
 			DBG(READ, ul_debug("unbalanced quotes at: %s", *value));
 			*cp = *value;
 			return -BLKID_ERR_CACHE;
 		}
 		(*value)++;
 		*end = '\0';
-		end++;
+		end = ++p;
 	} else {
 		end = skip_over_word(*value);
 		if (*end) {

programming_language: C
filename: save.c
change_type: ModificationType.MODIFY
diff: @@ -26,6 +26,21 @@
 
 #include "blkidP.h"
 
+
+static void save_quoted(const char *data, FILE *file)
+{
+	const char *p;
+
+	fputc('"', file);
+	for (p = data; p && *p; p++) {
+		if ((unsigned char) *p == 0x22 ||		/* " */
+		    (unsigned char) *p == 0x5c)			/* \ */
+			fputc('\\', file);
+
+		fputc(*p, file);
+	}
+	fputc('"', file);
+}
 static int save_dev(blkid_dev dev, FILE *file)
 {
 	struct list_head *p;
@@ -43,9 +58,14 @@ static int save_dev(blkid_dev dev, FILE *file)
 
 	if (dev->bid_pri)
 		fprintf(file, " PRI=\"%d\"", dev->bid_pri);
+
 	list_for_each(p, &dev->bid_tags) {
 		blkid_tag tag = list_entry(p, struct blkid_struct_tag, bit_tags);
-		fprintf(file, " %s=\"%s\"", tag->bit_name,tag->bit_val);
+
+		fputc(' ', file);			/* space between tags */
+		fputs(tag->bit_name, file);		/* tag NAME */
+		fputc('=', file);			/* separator between NAME and VALUE */
+		save_quoted(tag->bit_val, file);	/* tag "VALUE" */
 	}
 	fprintf(file, ">%s</device>\n", dev->bid_name);
 

programming_language: C
filename: blkid.8
change_type: ModificationType.MODIFY
diff: @@ -200,7 +200,10 @@ partitions.  This output format is \fBDEPRECATED\fR.
 .TP
 .B export
 print key=value pairs for easy import into the environment; this output format
-is automatically enabled when I/O Limits (\fB-i\fR option) are requested
+is automatically enabled when I/O Limits (\fB-i\fR option) are requested.
+
+The non-printing characters are encoded by ^ and M- notation and all
+potentially unsafe characters are escaped.
 .RE
 .TP
 .BI \-O " offset"

programming_language: Shell
filename: blkid.c
change_type: ModificationType.MODIFY
diff: @@ -306,7 +306,7 @@ static void print_value(int output, int num, const char *devname,
 			printf("DEVNAME=%s\n", devname);
 		fputs(name, stdout);
 		fputs("=", stdout);
-		safe_print(value, valsz, NULL);
+		safe_print(value, valsz, " \\\"'$`<>");
 		fputs("\n", stdout);
 
 	} else {
@@ -315,7 +315,7 @@ static void print_value(int output, int num, const char *devname,
 		fputs(" ", stdout);
 		fputs(name, stdout);
 		fputs("=\"", stdout);
-		safe_print(value, valsz, "\"");
+		safe_print(value, valsz, "\"\\");
 		fputs("\"", stdout);
 	}
 }

programming_language: C