linux-kernel - [PATCH v11 01/29] x86/fpu/xstate: Fix the state copy function to the XSTATE buffer

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Date:   Fri,  1 Oct 2021 15:37:00 -0700
From:   "Chang S. Bae" <chang.seok.bae@...el.com>
To:     bp@...e.de, luto@...nel.org, tglx@...utronix.de, mingo@...nel.org,
        x86@...nel.org
Cc:     len.brown@...el.com, lenb@...nel.org, dave.hansen@...el.com,
        thiago.macieira@...el.com, jing2.liu@...el.com,
        ravi.v.shankar@...el.com, linux-kernel@...r.kernel.org,
        chang.seok.bae@...el.com
Subject: [PATCH v11 01/29] x86/fpu/xstate: Fix the state copy function to the XSTATE buffer

Harden copy_uabi_to_xstate() so that it can handle the case where
__raw_xsave() returns NULL. This does not happen in practice today, but
theoretically could happen in the future.

Signed-off-by: Chang S. Bae <chang.seok.bae@...el.com>
Reviewed-by: Len Brown <len.brown@...el.com>
Cc: x86@...nel.org
Cc: linux-kernel@...r.kernel.org
---
Changes from v9:
* Add as a new patch (moved from Patch11). (Borislav Petkov)
---
 arch/x86/kernel/fpu/xstate.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index c8def1b7f8fb..fc1d529547e6 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -1132,6 +1132,9 @@ static int copy_uabi_to_xstate(struct xregs_state *xsave, const void *kbuf,
 		if (hdr.xfeatures & mask) {
 			void *dst = __raw_xsave_addr(xsave, i);
 
+			if (!dst)
+				continue;
+
 			offset = xstate_offsets[i];
 			size = xstate_sizes[i];
 
-- 
2.17.1