[merged] gen_init_cpio-avoid-stack-overflow-when-expanding.patch removed from -mm tree

[akpm@xxxxxxxxxxxxxxxxxxxx]

The patch titled
     Subject: gen_init_cpio: avoid stack overflow when expanding
has been removed from the -mm tree.  Its filename was
     gen_init_cpio-avoid-stack-overflow-when-expanding.patch

This patch was dropped because it was merged into mainline or a subsystem tree

------------------------------------------------------
From: Kees Cook <keescook@xxxxxxxxxxxx>
Subject: gen_init_cpio: avoid stack overflow when expanding

Fix possible overflow of the buffer used for expanding environment
variables when building file list.  In the extremely unlikely case of an
attacker having control over the environment variables visible to
gen_init_cpio, control over the contents of the file gen_init_cpio parses,
and gen_init_cpio was built without compiler hardening, the attacker can
gain arbitrary execution control via a stack buffer overflow.

$ cat usr/crash.list
file foo ${BIG}${BIG}${BIG}${BIG}${BIG}${BIG} 0755 0 0
$ BIG=$(perl -e 'print "A" x 4096;') ./usr/gen_init_cpio usr/crash.list
*** buffer overflow detected ***: ./usr/gen_init_cpio terminated

This also replaces the space-indenting with tabs.

Patch based on existing fix extracted from grsecurity.

Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Michal Marek <mmarek@xxxxxxx>
Cc: Brad Spengler <spender@xxxxxxxxxxxxxx>
Cc: PaX Team <pageexec@xxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---

 usr/gen_init_cpio.c |   41 ++++++++++++++++++++++-------------------
 1 file changed, 22 insertions(+), 19 deletions(-)

diff -puN usr/gen_init_cpio.c~gen_init_cpio-avoid-stack-overflow-when-expanding usr/gen_init_cpio.c
--- a/usr/gen_init_cpio.c~gen_init_cpio-avoid-stack-overflow-when-expanding
+++ a/usr/gen_init_cpio.c
@@ -303,7 +303,7 @@ static int cpio_mkfile(const char *name,
 	int retval;
 	int rc = -1;
 	int namesize;
-	int i;
+	unsigned int i;
 
 	mode |= S_IFREG;
 
@@ -381,25 +381,28 @@ error:
 
 static char *cpio_replace_env(char *new_location)
 {
-       char expanded[PATH_MAX + 1];
-       char env_var[PATH_MAX + 1];
-       char *start;
-       char *end;
-
-       for (start = NULL; (start = strstr(new_location, "${")); ) {
-               end = strchr(start, '}');
-               if (start < end) {
-                       *env_var = *expanded = '\0';
-                       strncat(env_var, start + 2, end - start - 2);
-                       strncat(expanded, new_location, start - new_location);
-                       strncat(expanded, getenv(env_var), PATH_MAX);
-                       strncat(expanded, end + 1, PATH_MAX);
-                       strncpy(new_location, expanded, PATH_MAX);
-               } else
-                       break;
-       }
+	char expanded[PATH_MAX + 1];
+	char env_var[PATH_MAX + 1];
+	char *start;
+	char *end;
+
+	for (start = NULL; (start = strstr(new_location, "${")); ) {
+		end = strchr(start, '}');
+		if (start < end) {
+			*env_var = *expanded = '\0';
+			strncat(env_var, start + 2, end - start - 2);
+			strncat(expanded, new_location, start - new_location);
+			strncat(expanded, getenv(env_var),
+				PATH_MAX - strlen(expanded));
+			strncat(expanded, end + 1,
+				PATH_MAX - strlen(expanded));
+			strncpy(new_location, expanded, PATH_MAX);
+			new_location[PATH_MAX] = 0;
+		} else
+			break;
+	}
 
-       return new_location;
+	return new_location;
 }
 
 
_

Patches currently in -mm which might be from keescook@xxxxxxxxxxxx are

linux-next.patch
fs-pstore-ramc-fix-up-section-annotations.patch
proc-dont-show-nonexistent-capabilities.patch

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