[PATCH 4.19 082/109] x86/fpu: Reset state for all signal restore failures
From: Sasha Levin <sashal@kernel.org>
Date: 2021-06-28 14:59:07
Also in:
lkml
Subsystem:
the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
From: Thomas Gleixner <redacted>
commit efa165504943f2128d50f63de0c02faf6dcceb0d upstream.
If access_ok() or fpregs_soft_set() fails in __fpu__restore_sig() then the
function just returns but does not clear the FPU state as it does for all
other fatal failures.
Clear the FPU state for these failures as well.
Fixes: 72a671ced66d ("x86, fpu: Unify signal handling code paths for x86 and x86_64 kernels")
Signed-off-by: Thomas Gleixner <redacted>
Signed-off-by: Borislav Petkov <redacted>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/87mtryyhhz.ffs@nanos.tec.linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/x86/kernel/fpu/signal.c | 31 ++++++++++++++++++++-----------
1 file changed, 20 insertions(+), 11 deletions(-)
diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c
index d99a8ee9e185..86a231338bbf 100644
--- a/arch/x86/kernel/fpu/signal.c
+++ b/arch/x86/kernel/fpu/signal.c@@ -272,6 +272,7 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size) int state_size = fpu_kernel_xstate_size; u64 xfeatures = 0; int fx_only = 0; + int ret = 0; ia32_fxstate &= (IS_ENABLED(CONFIG_X86_32) || IS_ENABLED(CONFIG_IA32_EMULATION));
@@ -281,15 +282,21 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size) return 0; } - if (!access_ok(VERIFY_READ, buf, size)) - return -EACCES; + if (!access_ok(VERIFY_READ, buf, size)) { + ret = -EACCES; + goto out_err; + } fpu__initialize(fpu); - if (!static_cpu_has(X86_FEATURE_FPU)) - return fpregs_soft_set(current, NULL, - 0, sizeof(struct user_i387_ia32_struct), - NULL, buf) != 0; + if (!static_cpu_has(X86_FEATURE_FPU)) { + ret = fpregs_soft_set(current, NULL, + 0, sizeof(struct user_i387_ia32_struct), + NULL, buf) != 0; + if (ret) + goto out_err; + return 0; + } if (use_xsave()) { struct _fpx_sw_bytes fx_sw_user;
@@ -349,6 +356,7 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size) fpu__restore(fpu); local_bh_enable(); + /* Failure is already handled */ return err; } else { /*
@@ -356,13 +364,14 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size) * state to the registers directly (with exceptions handled). */ user_fpu_begin(); - if (copy_user_to_fpregs_zeroing(buf_fx, xfeatures, fx_only)) { - fpu__clear(fpu); - return -1; - } + if (!copy_user_to_fpregs_zeroing(buf_fx, xfeatures, fx_only)) + return 0; + ret = -1; } - return 0; +out_err: + fpu__clear(fpu); + return ret; } static inline int xstate_sigframe_size(void)
--
2.30.2