This is a note to let you know that I've just added the patch titled
x86/fpu: Reset state for all signal restore failures
to the 4.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-fpu-reset-state-for-all-signal-restore-failures.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From efa165504943f2128d50f63de0c02faf6dcceb0d Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Date: Wed, 9 Jun 2021 21:18:00 +0200
Subject: x86/fpu: Reset state for all signal restore failures
From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
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 <tglx@xxxxxxxxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Link: https://lkml.kernel.org/r/87mtryyhhz.ffs@xxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kernel/fpu/signal.c | 31 ++++++++++++++++++++-----------
1 file changed, 20 insertions(+), 11 deletions(-)
--- a/arch/x86/kernel/fpu/signal.c
+++ b/arch/x86/kernel/fpu/signal.c
@@ -272,6 +272,7 @@ static int __fpu__restore_sig(void __use
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 __use
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 __use
fpu__restore(fpu);
local_bh_enable();
+ /* Failure is already handled */
return err;
} else {
/*
@@ -356,13 +364,14 @@ static int __fpu__restore_sig(void __use
* 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)
Patches currently in stable-queue which might be from tglx@xxxxxxxxxxxxx are
queue-4.19/x86-fpu-reset-state-for-all-signal-restore-failures.patch
