Commit ab676b7d authored by Kirill A. Shutemov's avatar Kirill A. Shutemov Committed by Linus Torvalds

pagemap: do not leak physical addresses to non-privileged userspace

As pointed by recent post[1] on exploiting DRAM physical imperfection,
/proc/PID/pagemap exposes sensitive information which can be used to do

This disallows anybody without CAP_SYS_ADMIN to read the pagemap.


[ Eventually we might want to do anything more finegrained, but for now
  this is the simple model.   - Linus ]
Signed-off-by: default avatarKirill A. Shutemov <>
Acked-by: default avatarKonstantin Khlebnikov <>
Acked-by: default avatarAndy Lutomirski <>
Cc: Pavel Emelyanov <>
Cc: Andrew Morton <>
Cc: Mark Seaborn <>
Signed-off-by: default avatarLinus Torvalds <>
parent 06e5801b
......@@ -1325,6 +1325,9 @@ static ssize_t pagemap_read(struct file *file, char __user *buf,
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");
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