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Update comment explaining the check, to reality.

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Discussed with:	jhb
Sponsored by:	The FreeBSD Foundation
MFC after:	3 days
This commit is contained in:
Konstantin Belousov 2018-01-11 12:07:24 +00:00
parent fc1689021f
commit 3ee6e65875
2 changed files with 6 additions and 10 deletions
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8
sys/amd64/amd64/support.S
View File

@ -249,12 +249,10 @@ ENTRY(copyout)
jz done_copyout
/*
* Check explicitly for non-user addresses. If 486 write protection
* is being used, this check is essential because we are in kernel
* mode so the h/w does not provide any protection against writing
* kernel addresses.
* Check explicitly for non-user addresses. This check is essential
* because it prevents usermode from writing into kernel. We do not
* verify that user did not specified a rogue address anywhere else.
*/
/*
* First, prevent address wrapping.
*/

8
sys/i386/i386/support.s
View File

@ -291,12 +291,10 @@ ENTRY(copyout)
jz done_copyout
/*
* Check explicitly for non-user addresses. If 486 write protection
* is being used, this check is essential because we are in kernel
* mode so the h/w does not provide any protection against writing
* kernel addresses.
* Check explicitly for non-user addresses. This check is essential
* because it prevents usermode from writing into kernel. We do not
* verify that user did not specified a rogue address anywhere else.
*/
/*
* First, prevent address wrapping.
*/