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authorEric Biggers <ebiggers3@gmail.com>2015-10-17 16:26:09 -0500
committerAl Viro <viro@zeniv.linux.org.uk>2015-11-11 02:18:26 -0500
commit6ae08069939f17422835448acae76bda8d96b16a (patch)
tree284390441dc289c394630aca998ed85b36442242 /fs
parentfs/pipe.c: preserve alloc_file() error code (diff)
downloadlinux-dev-6ae08069939f17422835448acae76bda8d96b16a.tar.xz
linux-dev-6ae08069939f17422835448acae76bda8d96b16a.zip
fs/pipe.c: return error code rather than 0 in pipe_write()
pipe_write() would return 0 if it failed to merge the beginning of the data to write with the last, partially filled pipe buffer. It should return an error code instead. Userspace programs could be confused by write() returning 0 when called with a nonzero 'count'. The EFAULT error case was a regression from f0d1bec9d5 ("new helper: copy_page_from_iter()"), while the ops->confirm() error case was a much older bug. Test program: #include <assert.h> #include <errno.h> #include <unistd.h> int main(void) { int fd[2]; char data[1] = {0}; assert(0 == pipe(fd)); assert(1 == write(fd[1], data, 1)); /* prior to this patch, write() returned 0 here */ assert(-1 == write(fd[1], NULL, 1)); assert(errno == EFAULT); } Cc: stable@vger.kernel.org # at least v3.15+ Signed-off-by: Eric Biggers <ebiggers3@gmail.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs')
-rw-r--r--fs/pipe.c9
1 files changed, 4 insertions, 5 deletions
diff --git a/fs/pipe.c b/fs/pipe.c
index 997de3464479..42cf8ddf0e55 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -366,18 +366,17 @@ pipe_write(struct kiocb *iocb, struct iov_iter *from)
int offset = buf->offset + buf->len;
if (ops->can_merge && offset + chars <= PAGE_SIZE) {
- int error = ops->confirm(pipe, buf);
- if (error)
+ ret = ops->confirm(pipe, buf);
+ if (ret)
goto out;
ret = copy_page_from_iter(buf->page, offset, chars, from);
if (unlikely(ret < chars)) {
- error = -EFAULT;
+ ret = -EFAULT;
goto out;
}
do_wakeup = 1;
- buf->len += chars;
- ret = chars;
+ buf->len += ret;
if (!iov_iter_count(from))
goto out;
}