3.19-stable review patch. If anyone has any objections, please let me know.
------------------ From: "Kirill A. Shutemov" <[email protected]> commit ab676b7d6fbf4b294bf198fb27ade5b0e865c7ce upstream. As pointed by recent post[1] on exploiting DRAM physical imperfection, /proc/PID/pagemap exposes sensitive information which can be used to do attacks. This disallows anybody without CAP_SYS_ADMIN to read the pagemap. [1] http://googleprojectzero.blogspot.com/2015/03/exploiting-dram-rowhammer-bug-to-gain.html [ Eventually we might want to do anything more finegrained, but for now this is the simple model. - Linus ] Signed-off-by: Kirill A. Shutemov <[email protected]> Acked-by: Konstantin Khlebnikov <[email protected]> Acked-by: Andy Lutomirski <[email protected]> Cc: Pavel Emelyanov <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Mark Seaborn <[email protected]> Signed-off-by: Linus Torvalds <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- fs/proc/task_mmu.c | 3 +++ 1 file changed, 3 insertions(+) --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -1326,6 +1326,9 @@ out: static int pagemap_open(struct inode *inode, struct file *file) { + /* do not disclose physical addresses: attack vector */ + if (!capable(CAP_SYS_ADMIN)) + return -EPERM; pr_warn_once("Bits 55-60 of /proc/PID/pagemap entries are about " "to stop being page-shift some time soon. See the " "linux/Documentation/vm/pagemap.txt for details.\n"); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
