diff options
author | Nicolas Schier <nicolas@fjasle.eu> | 2021-10-12 20:12:20 +0000 |
---|---|---|
committer | Masahiro Yamada <masahiroy@kernel.org> | 2021-10-24 13:48:40 +0900 |
commit | 4c9d410f32b3fac15ff1197c4b8746da6d11a17e (patch) | |
tree | 167560ddf497a9ffeffdbde83a394ebab451b01f /usr | |
parent | 6947fd96ae9bbe8c8c473a2199fd3edfd8b9f8c8 (diff) | |
download | linux-4c9d410f32b3fac15ff1197c4b8746da6d11a17e.tar.gz linux-4c9d410f32b3fac15ff1197c4b8746da6d11a17e.tar.bz2 linux-4c9d410f32b3fac15ff1197c4b8746da6d11a17e.zip |
initramfs: Check timestamp to prevent broken cpio archive
Cpio format reserves 8 bytes for an ASCII representation of a time_t timestamp.
While 2106-02-07 06:28:15 UTC (time_t = 0xffffffff) is still some years in the
future, a poorly chosen date string for KBUILD_BUILD_TIMESTAMP, converted into
seconds since the epoch, might lead to exceeded cpio timestamp limits that
result in a broken cpio archive. Add timestamp checks to prevent overrun of
the 8-byte cpio header field.
My colleague Thomas Kühnel discovered the behaviour, when we accidentally fed
SOURCE_DATE_EPOCH to KBUILD_BUILD_TIMESTAMP as is: some timestamps (e.g.
1607420928 = 2021-12-08 9:48:48 UTC) will be interpreted by `date` as a valid
date specification of science fictional times (here: year 160742). Even though
this is bad input for KBUILD_BUILD_TIMESTAMP, it should not break the initramfs
cpio format.
Signed-off-by: Nicolas Schier <nicolas@fjasle.eu>
Cc: Thomas Kühnel <thomas.kuehnel@avm.de>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Diffstat (limited to 'usr')
-rw-r--r-- | usr/gen_init_cpio.c | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/usr/gen_init_cpio.c b/usr/gen_init_cpio.c index bf5b98c6cf8d..0e2c8a5838b1 100644 --- a/usr/gen_init_cpio.c +++ b/usr/gen_init_cpio.c @@ -320,6 +320,12 @@ static int cpio_mkfile(const char *name, const char *location, goto error; } + if (buf.st_mtime > 0xffffffff) { + fprintf(stderr, "%s: Timestamp exceeds maximum cpio timestamp, clipping.\n", + location); + buf.st_mtime = 0xffffffff; + } + filebuf = malloc(buf.st_size); if (!filebuf) { fprintf (stderr, "out of memory\n"); @@ -551,6 +557,16 @@ int main (int argc, char *argv[]) } } + /* + * 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 + * specification. + */ + if (default_mtime > 0xffffffff) { + fprintf(stderr, "ERROR: Timestamp too large for cpio format\n"); + exit(1); + } + if (argc - optind != 1) { usage(argv[0]); exit(1); |