diff options
authorJann Horn <jannh@google.com>2019-06-28 12:06:46 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2019-06-29 16:43:45 +0800
commit867bfa4a5fcee66f2b25639acae718e8b28b25a5 (patch)
parent29b190fa774dd1b72a1a6f19687d55dc72ea83be (diff)
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@google.com Fixes: 287980e49ffc ("remove lots of IS_ERR_VALUE abuses") Signed-off-by: Jann Horn <jannh@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Kees Cook <keescook@chromium.org> Cc: Nicolas Pitre <nicolas.pitre@linaro.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Russell King <linux@armlinux.org.uk> Cc: Greg Ungerer <gerg@linux-m68k.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 files changed, 7 insertions, 16 deletions
diff --git a/fs/binfmt_flat.c b/fs/binfmt_flat.c
index 82a48e830018..e4b59e76afb0 100644
--- a/fs/binfmt_flat.c
+++ b/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 id, struct lib_info *libs)
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 = kernel_read(bprm.file, bprm.buf, BINPRM_BUF_SIZE, &pos);
- res = prepare_binprm(&bprm);
- if (!res)
+ if (res >= 0)
res = load_flat_file(&bprm, libs, id, NULL);
- abort_creds(bprm.cred);