Commit 5efb685b authored by Benjamin Gray's avatar Benjamin Gray Committed by Masahiro Yamada

initramfs: Check negative timestamp to prevent broken cpio archive

Similar to commit 4c9d410f ("initramfs: Check timestamp to prevent
broken cpio archive"), except asserts that the timestamp is
non-negative. This can happen when the KBUILD_BUILD_TIMESTAMP is a value
before UNIX epoch, which may be set when making reproducible builds that
don't want to look like they use a valid date.

While support for dates before 1970 might not be supported, this is more
about preventing undetected CPIO corruption. The printf's use a minimum
length format specifier, and will happily make the field longer than 8
characters if they need to.
Signed-off-by: default avatarBenjamin Gray <bgray@linux.ibm.com>
Reviewed-by: default avatarAndrew Donnellan <ajd@linux.ibm.com>
Tested-by: default avatarAndrew Donnellan <ajd@linux.ibm.com>
Signed-off-by: default avatarMasahiro Yamada <masahiroy@kernel.org>
parent aa7d233f
...@@ -353,6 +353,12 @@ static int cpio_mkfile(const char *name, const char *location, ...@@ -353,6 +353,12 @@ static int cpio_mkfile(const char *name, const char *location,
buf.st_mtime = 0xffffffff; buf.st_mtime = 0xffffffff;
} }
if (buf.st_mtime < 0) {
fprintf(stderr, "%s: Timestamp negative, clipping.\n",
location);
buf.st_mtime = 0;
}
if (buf.st_size > 0xffffffff) { if (buf.st_size > 0xffffffff) {
fprintf(stderr, "%s: Size exceeds maximum cpio file size\n", fprintf(stderr, "%s: Size exceeds maximum cpio file size\n",
location); location);
...@@ -602,10 +608,10 @@ int main (int argc, char *argv[]) ...@@ -602,10 +608,10 @@ int main (int argc, char *argv[])
/* /*
* Timestamps after 2106-02-07 06:28:15 UTC have an ascii hex time_t * Timestamps after 2106-02-07 06:28:15 UTC have an ascii hex time_t
* representation that exceeds 8 chars and breaks the cpio header * representation that exceeds 8 chars and breaks the cpio header
* specification. * specification. Negative timestamps similarly exceed 8 chars.
*/ */
if (default_mtime > 0xffffffff) { if (default_mtime > 0xffffffff || default_mtime < 0) {
fprintf(stderr, "ERROR: Timestamp too large for cpio format\n"); fprintf(stderr, "ERROR: Timestamp out of range for cpio format\n");
exit(1); exit(1);
} }
......
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