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Commit 6dfab366 authored by Ard Biesheuvel's avatar Ard Biesheuvel Committed by Jason A. Donenfeld
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FROMLIST: crypto: arm64/poly1305-neon - reorder PAC authentication with SP update 



PAC pointer authentication signs the return address against the value
of the stack pointer, to prevent stack overrun exploits from corrupting
the control flow. However, this requires that the AUTIASP is issued with
SP holding the same value as it held when the PAC value was generated.
The Poly1305 NEON code got this wrong, resulting in crashes on PAC
capable hardware.

Fixes: f569ca164751 ("crypto: arm64/poly1305 - incorporate OpenSSL/CRYPTOGAMS ...")
Signed-off-by: default avatarArd Biesheuvel <ardb@kernel.org>
Bug: 152722841
Link: https://lore.kernel.org/linux-crypto/20201026230027.25813-1-ardb@kernel.org/


Signed-off-by: default avatarJason A. Donenfeld <Jason@zx2c4.com>
Change-Id: Ib5282ac56ba5158c7d97195c2460701006bf82f6
parent 2c4c3ab8

arch/arm64/crypto/poly1305-armv8.pl

+1 −1
Original line number Diff line number Diff line
@@ -840,7 +840,6 @@ poly1305_blocks_neon: 
	 ldp	d14,d15,[sp,#64]

	addp	$ACC2,$ACC2,$ACC2

	 ldr	x30,[sp,#8]

	 .inst	0xd50323bf		// autiasp



	////////////////////////////////////////////////////////////////

	// lazy reduction, but without narrowing
@@ -882,6 +881,7 @@ poly1305_blocks_neon: 
	str	x4,[$ctx,#8]		// set is_base2_26



	ldr	x29,[sp],#80

	 .inst	0xd50323bf		// autiasp

	ret

.size	poly1305_blocks_neon,.-poly1305_blocks_neon

arch/arm64/crypto/poly1305-core.S_shipped

+1 −1
Original line number Diff line number Diff line
@@ -779,7 +779,6 @@ poly1305_blocks_neon: 
	 ldp	d14,d15,[sp,#64]

	addp	v21.2d,v21.2d,v21.2d

	 ldr	x30,[sp,#8]

	 .inst	0xd50323bf		// autiasp



	////////////////////////////////////////////////////////////////

	// lazy reduction, but without narrowing
@@ -821,6 +820,7 @@ poly1305_blocks_neon: 
	str	x4,[x0,#8]		// set is_base2_26



	ldr	x29,[sp],#80

	 .inst	0xd50323bf		// autiasp

	ret

.size	poly1305_blocks_neon,.-poly1305_blocks_neon