A-Team_Digital_Solutions/android_kernel_motorola_sm6375
Watch
2
0
Fork
You've already forked android_kernel_motorola_sm6375
 0
mirror of https://github.com/BobTheBlinker/android_kernel_motorola_sm6375.git synced 2026-10-30 19:51:31 -04:00
Code Issues Projects Releases Packages Wiki Activity

dax: explain how read(2)/write(2) addresses are validated

Browse source 
Add a comment explaining how the user addresses provided to read(2) and
write(2) are validated in the DAX I/O path.

We call dax_copy_from_iter() or copy_to_iter() on these without calling
access_ok() first in the DAX code, and there was a concern that the user
might be able to read/write to arbitrary kernel addresses with this
path.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ross Zwisler <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Dan Williams <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
Ross Zwisler 2017-09-06 16:18:54 -07:00 • committed by Linus Torvalds
commit a2e050f5a9
1 changed files with 5 additions and 0 deletions
Download patch file Download diff file Expand all files Collapse all files

5
fs/dax.c
View file

@ -1004,6 +1004,11 @@ dax_iomap_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
if (map_len > end - pos)
map_len = end - pos;
/*
* The userspace address for the memory copy has already been
* validated via access_ok() in either vfs_read() or
* vfs_write(), depending on which operation we are doing.
*/
if (iov_iter_rw(iter) == WRITE)
map_len = dax_copy_from_iter(dax_dev, pgoff, kaddr,
map_len, iter);