From: Darrick J. Wong <darrick.wong@oracle.com>
Date: Thu, 30 Jan 2020 18:40:54 +0000 (-0500)
Subject: xfs_io: fix pwrite/pread length truncation on 32-bit systems
X-Git-Tag: v5.5.0-rc1~55
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=4eafc4d3fdf088dd66b64ff6718c716ed84d457f;p=users%2Fhch%2Fxfsprogs.git

xfs_io: fix pwrite/pread length truncation on 32-bit systems

The pwrite and pread commands in xfs_io accept an operation length that
can be any quantity that fits in a long long int; and loops to handle
the cases where the operation length is larger than the IO buffer.

Weirdly, the do_ functions contain code to shorten the operation to the
IO buffer size but the @count parameter is size_t, which means that for
a large argument on a 32-bit system, we rip off the upper bits of the
length, turning your 8GB write into a 0 byte write, which does nothing.

This was found by running generic/175 and observing that the 8G test
file it creates has zero length after the operation:

wrote 0/8589934592 bytes at offset 0
0.000000 bytes, 0 ops; 0.0001 sec (0.000000 bytes/sec and 0.0000 ops/sec)

Fix this by pushing long long count all the way through the call stack.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>
---

diff --git a/io/pread.c b/io/pread.c
index 1b4352be1..d52e21d96 100644
--- a/io/pread.c
+++ b/io/pread.c
@@ -164,7 +164,7 @@ static ssize_t
 do_preadv(
 	int		fd,
 	off64_t		offset,
-	size_t		count)
+	long long	count)
 {
 	int		vecs = 0;
 	ssize_t		oldlen = 0;
@@ -199,7 +199,7 @@ static ssize_t
 do_pread(
 	int		fd,
 	off64_t		offset,
-	size_t		count,
+	long long	count,
 	size_t		buffer_size)
 {
 	if (!vectors)
diff --git a/io/pwrite.c b/io/pwrite.c
index ccf14be92..1c28612f3 100644
--- a/io/pwrite.c
+++ b/io/pwrite.c
@@ -54,8 +54,8 @@ static ssize_t
 do_pwritev(
 	int		fd,
 	off64_t		offset,
-	size_t		count,
-	int 		pwritev2_flags)
+	long long	count,
+	int		pwritev2_flags)
 {
 	int vecs = 0;
 	ssize_t oldlen = 0;
@@ -97,7 +97,7 @@ static ssize_t
 do_pwrite(
 	int		fd,
 	off64_t		offset,
-	size_t		count,
+	long long	count,
 	size_t		buffer_size,
 	int		pwritev2_flags)
 {