The patch titled
Subject: gen_init_cpio: fix short read file handling
has been added to the -mm tree. Its filename is
gen_init_cpio-fix-short-read-file-handling.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/gen_init_cpio-fix-short-read-file-handling.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/gen_init_cpio-fix-short-read-file-handling.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: David Disseldorp <ddiss@xxxxxxx>
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@xxxxxxx
Signed-off-by: David Disseldorp <ddiss@xxxxxxx>
Reviewed-by: Martin Wilck <mwilck@xxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Christian Brauner <christian.brauner@xxxxxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
usr/gen_init_cpio.c | 44 +++++++++++++++++++++++-------------------
1 file changed, 25 insertions(+), 19 deletions(-)
--- a/usr/gen_init_cpio.c~gen_init_cpio-fix-short-read-file-handling
+++ a/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,
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,
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,
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;
}
_
Patches currently in -mm which might be from ddiss@xxxxxxx are
initramfs-refactor-do_header-cpio-magic-checks.patch
initramfs-make-dir_entryname-a-flexible-array-member.patch
initramfs-add-initramfs_preserve_mtime-kconfig-option.patch
gen_init_cpio-fix-short-read-file-handling.patch
gen_init_cpio-support-file-checksum-archiving.patch
initramfs-support-cpio-extraction-with-file-checksums.patch
