Commit 7fe1e79b59ba ("configfs: implement the .read_iter and .write_iter
methods") changed the simple_read_from_buffer() calls into copy_to_iter()
calls and the simple_write_to_buffer() calls into copy_from_iter() calls.
The simple*buffer() methods update the file offset (*ppos) but the read and
write iterators not yet. Make the read and write iterators update the file
offset (iocb->ki_pos).
This patch has been tested as follows:
# modprobe target_core_user
# dd if=/sys/kernel/config/target/dbroot bs=1
/var/target
12+0 records in
12+0 records out
12 bytes copied, 9.5539e-05 s, 126 kB/s
# cd /sys/kernel/config/acpi/table
# mkdir test
# cd test
# dmesg -c >/dev/null; printf 'SSDT\x8\0\0\0abcdefghijklmnopqrstuvwxyz' | dd of=aml bs=1; dmesg -c
34+0 records in
34+0 records out
34 bytes copied, 0.010627 s, 3.2 kB/s
[ 261.056551] ACPI configfs: invalid table length
Reported-by: Yanko Kaneti <[email protected]>
Cc: Yanko Kaneti <[email protected]>
Fixes: 7fe1e79b59ba ("configfs: implement the .read_iter and .write_iter methods")
Signed-off-by: Bart Van Assche <[email protected]>
---
fs/configfs/file.c | 29 ++++++++++++++++++++++-------
1 file changed, 22 insertions(+), 7 deletions(-)
diff --git a/fs/configfs/file.c b/fs/configfs/file.c
index 2f63bf3a7325..5a0be9985bae 100644
--- a/fs/configfs/file.c
+++ b/fs/configfs/file.c
@@ -91,7 +91,10 @@ static ssize_t configfs_read_iter(struct kiocb *iocb, struct iov_iter *to)
}
pr_debug("%s: count = %zd, pos = %lld, buf = %s\n",
__func__, iov_iter_count(to), iocb->ki_pos, buffer->page);
- retval = copy_to_iter(buffer->page, buffer->count, to);
+ if (iocb->ki_pos >= buffer->count)
+ goto out;
+ retval = copy_to_iter(buffer->page + iocb->ki_pos,
+ buffer->count - iocb->ki_pos, to);
iocb->ki_pos += retval;
if (retval == 0)
retval = -EFAULT;
@@ -162,7 +165,10 @@ static ssize_t configfs_bin_read_iter(struct kiocb *iocb, struct iov_iter *to)
buffer->needs_read_fill = 0;
}
- retval = copy_to_iter(buffer->bin_buffer, buffer->bin_buffer_size, to);
+ if (iocb->ki_pos >= buffer->bin_buffer_size)
+ goto out;
+ retval = copy_to_iter(buffer->bin_buffer + iocb->ki_pos,
+ buffer->bin_buffer_size - iocb->ki_pos, to);
iocb->ki_pos += retval;
if (retval == 0)
retval = -EFAULT;
@@ -171,21 +177,28 @@ static ssize_t configfs_bin_read_iter(struct kiocb *iocb, struct iov_iter *to)
return retval;
}
-static int fill_write_buffer(struct configfs_buffer *buffer,
+/* Fill [buffer, buffer + pos) with data coming from @from. */
+static int fill_write_buffer(struct configfs_buffer *buffer, loff_t pos,
struct iov_iter *from)
{
+ loff_t to_copy;
int copied;
+ u8 *to;
if (!buffer->page)
buffer->page = (char *)__get_free_pages(GFP_KERNEL, 0);
if (!buffer->page)
return -ENOMEM;
- copied = copy_from_iter(buffer->page, SIMPLE_ATTR_SIZE - 1, from);
+ to_copy = SIMPLE_ATTR_SIZE - 1 - pos;
+ if (to_copy <= 0)
+ return 0;
+ to = buffer->page + pos;
+ copied = copy_from_iter(to, to_copy, from);
buffer->needs_read_fill = 1;
/* if buf is assumed to contain a string, terminate it by \0,
* so e.g. sscanf() can scan the string easily */
- buffer->page[copied] = 0;
+ to[copied] = 0;
return copied ? : -EFAULT;
}
@@ -217,7 +230,7 @@ static ssize_t configfs_write_iter(struct kiocb *iocb, struct iov_iter *from)
ssize_t len;
mutex_lock(&buffer->mutex);
- len = fill_write_buffer(buffer, from);
+ len = fill_write_buffer(buffer, iocb->ki_pos, from);
if (len > 0)
len = flush_write_buffer(file, buffer, len);
if (len > 0)
@@ -272,7 +285,9 @@ static ssize_t configfs_bin_write_iter(struct kiocb *iocb,
buffer->bin_buffer_size = end_offset;
}
- len = copy_from_iter(buffer->bin_buffer, buffer->bin_buffer_size, from);
+ len = copy_from_iter(buffer->bin_buffer + iocb->ki_pos,
+ buffer->bin_buffer_size - iocb->ki_pos, from);
+ iocb->ki_pos += len;
out:
mutex_unlock(&buffer->mutex);
return len ? : -EFAULT;