6.12-stable review patch. If anyone has any objections, please let me know.
------------------
From: Keir Fraser keirf@google.com
commit a13bfa4fe0d6949cea14718df2d1fe84c38cd113 upstream.
The source register is not used for SET* and reading it can result in a UBSAN out-of-bounds array access error, specifically when the MOPS exception is taken from a SET* sequence with XZR (reg 31) as the source. Architecturally this is the only case where a src/dst/size field in the ESR can be reported as 31.
Prior to 2de451a329cf662b the code in do_el0_mops() was benign as the use of pt_regs_read_reg() prevented the out-of-bounds access.
Fixes: 2de451a329cf ("KVM: arm64: Add handler for MOPS exceptions") Cc: stable@vger.kernel.org # 6.12.x Cc: Kristina Martsenko kristina.martsenko@arm.com Cc: Will Deacon will@kernel.org Cc: stable@vger.kernel.org Reviewed-by: Marc Zyngier maz@kernel.org Signed-off-by: Keir Fraser keirf@google.com Reviewed-by: Kristina Martšenko kristina.martsenko@arm.com Acked-by: Mark Rutland mark.rutland@arm.com Link: https://lore.kernel.org/r/20250326110448.3792396-1-keirf@google.com Signed-off-by: Catalin Marinas catalin.marinas@arm.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/arm64/include/asm/traps.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/include/asm/traps.h b/arch/arm64/include/asm/traps.h index d780d1bd2eac..82cf1f879c61 100644 --- a/arch/arm64/include/asm/traps.h +++ b/arch/arm64/include/asm/traps.h @@ -109,10 +109,9 @@ static inline void arm64_mops_reset_regs(struct user_pt_regs *regs, unsigned lon int dstreg = ESR_ELx_MOPS_ISS_DESTREG(esr); int srcreg = ESR_ELx_MOPS_ISS_SRCREG(esr); int sizereg = ESR_ELx_MOPS_ISS_SIZEREG(esr); - unsigned long dst, src, size; + unsigned long dst, size;
dst = regs->regs[dstreg]; - src = regs->regs[srcreg]; size = regs->regs[sizereg];
/* @@ -129,6 +128,7 @@ static inline void arm64_mops_reset_regs(struct user_pt_regs *regs, unsigned lon } } else { /* CPY* instruction */ + unsigned long src = regs->regs[srcreg]; if (!(option_a ^ wrong_option)) { /* Format is from Option B */ if (regs->pstate & PSR_N_BIT) {