Skip to main content

Browse the archive

https://github.com/torvalds/linux
27 March 2024, 02:37:15 UTC
Revision 9b7b819ca1e508195feed5ece558dca66adeef05 authored by Helge Deller on 04 June 2015, 21:57:18 UTC, committed by Helge Deller on 04 June 2015, 21:57:18 UTC 
compat: cleanup coding in compat_get_bitmap() and compat_put_bitmap()
 
In the functions compat_get_bitmap() and compat_put_bitmap() the
variable nr_compat_longs stores how many compat_ulong_t words should be
copied in a loop.

The copy loop itself is this:
  if (nr_compat_longs-- > 0) {
      if (__get_user(um, umask)) return -EFAULT;
  } else {
      um = 0;
  }

Since nr_compat_longs gets unconditionally decremented in each loop and
since it's type is unsigned this could theoretically lead to out of
bounds accesses to userspace if nr_compat_longs wraps around to
(unsigned)(-1).

Although the callers currently do not trigger out-of-bounds accesses, we
should better implement the loop in a safe way to completely avoid such
warp-arounds.

Signed-off-by: Helge Deller <deller@gmx.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
1 parent ff25ea8
History
Tip revision: 9b7b819ca1e508195feed5ece558dca66adeef05 authored by Helge Deller on 04 June 2015, 21:57:18 UTC
compat: cleanup coding in compat_get_bitmap() and compat_put_bitmap()
Tip revision: 9b7b819
File Mode Size
Documentation
arch
block
crypto
drivers
firmware
fs
include
init
ipc
kernel
lib
mm
net
samples
scripts
security
sound
tools
usr
virt
.gitignore -rw-r--r-- 1.2 KB
.mailmap -rw-r--r-- 4.9 KB
COPYING -rw-r--r-- 18.3 KB
CREDITS -rw-r--r-- 94.7 KB
Kbuild -rw-r--r-- 2.1 KB
Kconfig -rw-r--r-- 252 bytes
MAINTAINERS -rw-r--r-- 303.0 KB
Makefile -rw-r--r-- 53.1 KB
README -rw-r--r-- 18.2 KB
REPORTING-BUGS -rw-r--r-- 7.3 KB

README

back to top