queue-4.19/vfs-fix-preadv64v2-and-pwritev64v2-compat-syscalls-w.patch

   1 From bf9901d0c75ae562dcbbfebe290160e89f48d3c6 Mon Sep 17 00:00:00 2001
   2 From: Aurelien Jarno <aurelien@aurel32.net>
   3 Date: Thu, 6 Dec 2018 20:05:34 +0100
   4 Subject: vfs: fix preadv64v2 and pwritev64v2 compat syscalls with offset == -1
   5
   6 [ Upstream commit cc4b1242d7e3b42eed73881fc749944146493e4f ]
   7
   8 The preadv2 and pwritev2 syscalls are supposed to emulate the readv and
   9 writev syscalls when offset == -1. Therefore the compat code should
  10 check for offset before calling do_compat_preadv64 and
  11 do_compat_pwritev64. This is the case for the preadv2 and pwritev2
  12 syscalls, but handling of offset == -1 is missing in their 64-bit
  13 equivalent.
  14
  15 This patch fixes that, calling do_compat_readv and do_compat_writev when
  16 offset == -1. This fixes the following glibc tests on x32:
  17  - misc/tst-preadvwritev2
  18  - misc/tst-preadvwritev64v2
  19
  20 Cc: Alexander Viro <viro@zeniv.linux.org.uk>
  21 Cc: H.J. Lu <hjl.tools@gmail.com>
  22 Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
  23 Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
  24 Signed-off-by: Sasha Levin <sashal@kernel.org>
  25 ---
  26  fs/read_write.c | 6 ++++++
  27  1 file changed, 6 insertions(+)
  28
  29 diff --git a/fs/read_write.c b/fs/read_write.c
  30 index 8a2737f0d61d..562974a0616c 100644
  31 --- a/fs/read_write.c
  32 +++ b/fs/read_write.c
  33 @@ -1241,6 +1241,9 @@ COMPAT_SYSCALL_DEFINE5(preadv64v2, unsigned long, fd,
  34                 const struct compat_iovec __user *,vec,
  35                 unsigned long, vlen, loff_t, pos, rwf_t, flags)
  36  {
  37 +       if (pos == -1)
  38 +               return do_compat_readv(fd, vec, vlen, flags);
  39 +
  40         return do_compat_preadv64(fd, vec, vlen, pos, flags);
  41  }
  42  #endif
  43 @@ -1347,6 +1350,9 @@ COMPAT_SYSCALL_DEFINE5(pwritev64v2, unsigned long, fd,
  44                 const struct compat_iovec __user *,vec,
  45                 unsigned long, vlen, loff_t, pos, rwf_t, flags)
  46  {
  47 +       if (pos == -1)
  48 +               return do_compat_writev(fd, vec, vlen, flags);
  49 +
  50         return do_compat_pwritev64(fd, vec, vlen, pos, flags);
  51  }
  52  #endif
  53 --
  54 2.19.1
  55