The patch titled
Subject: fs/binfmt_flat.c: make load_flat_shared_library() work
has been added to the -mm tree. Its filename is
binfmt_flat-make-load_flat_shared_library-work.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/binfmt_flat-make-load_flat_shared_library-work.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/binfmt_flat-make-load_flat_shared_library-work.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: Jann Horn <jannh@xxxxxxxxxx>
Subject: fs/binfmt_flat.c: make load_flat_shared_library() work
load_flat_shared_library() is broken: It only calls load_flat_file() if
prepare_binprm() returns zero, but prepare_binprm() returns the number of
bytes read - so this only happens if the file is empty.
Instead, call into load_flat_file() if the number of bytes read is
non-negative. (Even if the number of bytes is zero - in that case,
load_flat_file() will see nullbytes and return a nice -ENOEXEC.)
In addition, remove the code related to bprm creds and stop using
prepare_binprm() - this code is loading a library, not a main executable,
and it only actually uses the members "buf", "file" and "filename" of the
linux_binprm struct. Instead, call kernel_read() directly.
Link: http://lkml.kernel.org/r/20190524201817.16509-1-jannh@xxxxxxxxxx
Fixes: 287980e49ffc ("remove lots of IS_ERR_VALUE abuses")
Signed-off-by: Jann Horn <jannh@xxxxxxxxxx>
Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Nicolas Pitre <nicolas.pitre@xxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
Cc: Russell King <linux@xxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/binfmt_flat.c | 23 +++++++----------------
1 file changed, 7 insertions(+), 16 deletions(-)
--- a/fs/binfmt_flat.c~binfmt_flat-make-load_flat_shared_library-work
+++ a/fs/binfmt_flat.c
@@ -856,9 +856,14 @@ err:
static int load_flat_shared_library(int id, struct lib_info *libs)
{
+ /*
+ * This is a fake bprm struct; only the members "buf", "file" and
+ * "filename" are actually used.
+ */
struct linux_binprm bprm;
int res;
char buf[16];
+ loff_t pos = 0;
memset(&bprm, 0, sizeof(bprm));
@@ -872,25 +877,11 @@ static int load_flat_shared_library(int
if (IS_ERR(bprm.file))
return res;
- bprm.cred = prepare_exec_creds();
- res = -ENOMEM;
- if (!bprm.cred)
- goto out;
-
- /* We don't really care about recalculating credentials at this point
- * as we're past the point of no return and are dealing with shared
- * libraries.
- */
- bprm.called_set_creds = 1;
-
- res = prepare_binprm(&bprm);
+ res = kernel_read(bprm.file, bprm.buf, BINPRM_BUF_SIZE, &pos);
- if (!res)
+ if (res >= 0)
res = load_flat_file(&bprm, libs, id, NULL);
- abort_creds(bprm.cred);
-
-out:
allow_write_access(bprm.file);
fput(bprm.file);
_
Patches currently in -mm which might be from jannh@xxxxxxxxxx are
binfmt_flat-make-load_flat_shared_library-work.patch
