4.9-stable review patch. If anyone has any objections, please let me know.
------------------
[ Upstream commit cc4b1242d7e3b42eed73881fc749944146493e4f ]
The preadv2 and pwritev2 syscalls are supposed to emulate the readv and
writev syscalls when offset == -1. Therefore the compat code should
check for offset before calling do_compat_preadv64 and
do_compat_pwritev64. This is the case for the preadv2 and pwritev2
syscalls, but handling of offset == -1 is missing in their 64-bit
equivalent.
This patch fixes that, calling do_compat_readv and do_compat_writev when
offset == -1. This fixes the following glibc tests on x32:
- misc/tst-preadvwritev2
- misc/tst-preadvwritev64v2
Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: H.J. Lu <hjl.tools@xxxxxxxxx>
Signed-off-by: Aurelien Jarno <aurelien@xxxxxxxxxxx>
Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
fs/read_write.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/fs/read_write.c b/fs/read_write.c
index 9819f7c6c8c5..6ab67b860159 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1204,6 +1204,9 @@ COMPAT_SYSCALL_DEFINE5(preadv64v2, unsigned long, fd,
const struct compat_iovec __user *,vec,
unsigned long, vlen, loff_t, pos, int, flags)
{
+ if (pos == -1)
+ return do_compat_readv(fd, vec, vlen, flags);
+
return do_compat_preadv64(fd, vec, vlen, pos, flags);
}
#endif
@@ -1310,6 +1313,9 @@ COMPAT_SYSCALL_DEFINE5(pwritev64v2, unsigned long, fd,
const struct compat_iovec __user *,vec,
unsigned long, vlen, loff_t, pos, int, flags)
{
+ if (pos == -1)
+ return do_compat_writev(fd, vec, vlen, flags);
+
return do_compat_pwritev64(fd, vec, vlen, pos, flags);
}
#endif
--
2.19.1
