From 3a2699cfbe317f6e1b9c84d2f10ab7debb1c79dc Mon Sep 17 00:00:00 2001 From: David Disseldorp Date: Mon, 9 May 2022 18:29:20 -0700 Subject: gen_init_cpio: fix short read file handling When processing a "file" entry, gen_init_cpio attempts to allocate a buffer large enough to stage the entire contents of the source file. It then attempts to fill the buffer via a single read() call and subsequently writes out the entire buffer length, without checking that read() returned the full length, potentially writing uninitialized buffer memory. Fix this by breaking up file I/O into 64k chunks and only writing the length returned by the prior read() call. Link: https://lkml.kernel.org/r/20220404093429.27570-5-ddiss@suse.de Signed-off-by: David Disseldorp Reviewed-by: Martin Wilck Cc: Al Viro Cc: Christian Brauner Cc: Matthew Wilcox (Oracle) Signed-off-by: Andrew Morton --- usr/gen_init_cpio.c | 44 +++++++++++++++++++++++++------------------- 1 file changed, 25 insertions(+), 19 deletions(-) (limited to 'usr') diff --git a/usr/gen_init_cpio.c b/usr/gen_init_cpio.c index 0e2c8a5838b1..9a0f8c37273a 100644 --- a/usr/gen_init_cpio.c +++ b/usr/gen_init_cpio.c @@ -20,6 +20,7 @@ #define xstr(s) #s #define str(s) xstr(s) +#define MIN(a, b) ((a) < (b) ? (a) : (b)) static unsigned int offset; static unsigned int ino = 721; @@ -297,9 +298,8 @@ static int cpio_mkfile(const char *name, const char *location, unsigned int nlinks) { char s[256]; - char *filebuf = NULL; struct stat buf; - long size; + unsigned long size; int file = -1; int retval; int rc = -1; @@ -326,22 +326,17 @@ static int cpio_mkfile(const char *name, const char *location, buf.st_mtime = 0xffffffff; } - filebuf = malloc(buf.st_size); - if (!filebuf) { - fprintf (stderr, "out of memory\n"); - goto error; - } - - retval = read (file, filebuf, buf.st_size); - if (retval < 0) { - fprintf (stderr, "Can not read %s file\n", location); + if (buf.st_size > 0xffffffff) { + fprintf(stderr, "%s: Size exceeds maximum cpio file size\n", + location); goto error; } size = 0; for (i = 1; i <= nlinks; i++) { /* data goes on last link */ - if (i == nlinks) size = buf.st_size; + if (i == nlinks) + size = buf.st_size; if (name[0] == '/') name++; @@ -366,23 +361,34 @@ static int cpio_mkfile(const char *name, const char *location, push_string(name); push_pad(); - if (size) { - if (fwrite(filebuf, size, 1, stdout) != 1) { + while (size) { + unsigned char filebuf[65536]; + ssize_t this_read; + size_t this_size = MIN(size, sizeof(filebuf)); + + this_read = read(file, filebuf, this_size); + if (this_read <= 0 || this_read > this_size) { + fprintf(stderr, "Can not read %s file\n", location); + goto error; + } + + if (fwrite(filebuf, this_read, 1, stdout) != 1) { fprintf(stderr, "writing filebuf failed\n"); goto error; } - offset += size; - push_pad(); + offset += this_read; + size -= this_read; } + push_pad(); name += namesize; } ino++; rc = 0; - + error: - if (filebuf) free(filebuf); - if (file >= 0) close(file); + if (file >= 0) + close(file); return rc; } -- cgit v1.2.3