From: "tip-bot2 for Daniel Vetter" <tip-bot2@linutronix.de>
To: linux-tip-commits@vger.kernel.org
Cc: Jason Gunthorpe <jgg@ziepe.ca>,
Daniel Vetter <daniel.vetter@intel.com>,
Borislav Petkov <bp@suse.de>, Jarkko Sakkinen <jarkko@kernel.org>,
x86@kernel.org, linux-kernel@vger.kernel.org
Subject: [tip: x86/sgx] x86/sgx: Drop racy follow_pfn() check
Date: Fri, 05 Feb 2021 09:55:06 -0000 [thread overview]
Message-ID: <161251890694.23325.7141350574807037445.tip-bot2@tip-bot2> (raw)
In-Reply-To: <20210204184519.2809313-1-daniel.vetter@ffwll.ch>
The following commit has been merged into the x86/sgx branch of tip:
Commit-ID: dc9b7be557ca94301ea5c06c0d72307e642ffb18
Gitweb: https://git.kernel.org/tip/dc9b7be557ca94301ea5c06c0d72307e642ffb18
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
AuthorDate: Thu, 04 Feb 2021 19:45:19 +01:00
Committer: Borislav Petkov <bp@suse.de>
CommitterDate: Fri, 05 Feb 2021 10:45:11 +01:00
x86/sgx: Drop racy follow_pfn() check
PTE insertion is fundamentally racy, and this check doesn't do anything
useful. Quoting Sean:
"Yeah, it can be whacked. The original, never-upstreamed code asserted
that the resolved PFN matched the PFN being installed by the fault
handler as a sanity check on the SGX driver's EPC management. The
WARN assertion got dropped for whatever reason, leaving that useless
chunk."
Jason stumbled over this as a new user of follow_pfn(), and I'm trying
to get rid of unsafe callers of that function so it can be locked down
further.
This is independent prep work for the referenced patch series:
https://lore.kernel.org/dri-devel/20201127164131.2244124-1-daniel.vetter@ffwll.ch/
Fixes: 947c6e11fa43 ("x86/sgx: Add ptrace() support for the SGX driver")
Reported-by: Jason Gunthorpe <jgg@ziepe.ca>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Link: https://lkml.kernel.org/r/20210204184519.2809313-1-daniel.vetter@ffwll.ch
---
arch/x86/kernel/cpu/sgx/encl.c | 8 --------
1 file changed, 8 deletions(-)
diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c
index ee50a50..20a2dd5 100644
--- a/arch/x86/kernel/cpu/sgx/encl.c
+++ b/arch/x86/kernel/cpu/sgx/encl.c
@@ -141,7 +141,6 @@ static vm_fault_t sgx_vma_fault(struct vm_fault *vmf)
struct sgx_encl_page *entry;
unsigned long phys_addr;
struct sgx_encl *encl;
- unsigned long pfn;
vm_fault_t ret;
encl = vma->vm_private_data;
@@ -168,13 +167,6 @@ static vm_fault_t sgx_vma_fault(struct vm_fault *vmf)
phys_addr = sgx_get_epc_phys_addr(entry->epc_page);
- /* Check if another thread got here first to insert the PTE. */
- if (!follow_pfn(vma, addr, &pfn)) {
- mutex_unlock(&encl->lock);
-
- return VM_FAULT_NOPAGE;
- }
-
ret = vmf_insert_pfn(vma, addr, PFN_DOWN(phys_addr));
if (ret != VM_FAULT_NOPAGE) {
mutex_unlock(&encl->lock);
prev parent reply other threads:[~2021-02-05 9:58 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-04 18:45 [PATCH] x86/sgx: Drop racy follow_pfn check Daniel Vetter
2021-02-05 2:26 ` Jarkko Sakkinen
2021-02-05 2:26 ` Jarkko Sakkinen
2021-02-05 7:43 ` Daniel Vetter
2021-02-07 21:16 ` Jarkko Sakkinen
2021-02-05 9:55 ` tip-bot2 for Daniel Vetter [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=161251890694.23325.7141350574807037445.tip-bot2@tip-bot2 \
--to=tip-bot2@linutronix.de \
--cc=bp@suse.de \
--cc=daniel.vetter@intel.com \
--cc=jarkko@kernel.org \
--cc=jgg@ziepe.ca \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-tip-commits@vger.kernel.org \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).