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authorAndy Lutomirski <luto@kernel.org>2022-02-14 13:05:49 +0100
committerBorislav Petkov <bp@suse.de>2022-02-18 11:23:21 +0100
commit44cad52cc14ae10062f142ec16ede489bccf4469 (patch)
treed2a0c3287e9e54c622e3f79c74ce7ea900005483 /arch
parente5733d8c89c3b57c8fcd40b8acf508388fabaa42 (diff)
x86/ptrace: Fix xfpregs_set()'s incorrect xmm clearing
xfpregs_set() handles 32-bit REGSET_XFP and 64-bit REGSET_FP. The actual code treats these regsets as modern FX state (i.e. the beginning part of XSTATE). The declarations of the regsets thought they were the legacy i387 format. The code thought they were the 32-bit (no xmm8..15) variant of XSTATE and, for good measure, made the high bits disappear by zeroing the wrong part of the buffer. The latter broke ptrace, and everything else confused anyone trying to understand the code. In particular, the nonsense definitions of the regsets confused me when I wrote this code. Clean this all up. Change the declarations to match reality (which shouldn't change the generated code, let alone the ABI) and fix xfpregs_set() to clear the correct bits and to only do so for 32-bit callers. Fixes: 6164331d15f7 ("x86/fpu: Rewrite xfpregs_set()") Reported-by: Luís Ferreira <contact@lsferreira.net> Signed-off-by: Andy Lutomirski <luto@kernel.org> Signed-off-by: Borislav Petkov <bp@suse.de> Cc: <stable@vger.kernel.org> Link: https://bugzilla.kernel.org/show_bug.cgi?id=215524 Link: https://lore.kernel.org/r/YgpFnZpF01WwR8wU@zn.tnic
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kernel/fpu/regset.c9
-rw-r--r--arch/x86/kernel/ptrace.c4
2 files changed, 6 insertions, 7 deletions
diff --git a/arch/x86/kernel/fpu/regset.c b/arch/x86/kernel/fpu/regset.c
index 437d7c930c0b..75ffaef8c299 100644
--- a/arch/x86/kernel/fpu/regset.c
+++ b/arch/x86/kernel/fpu/regset.c
@@ -91,11 +91,9 @@ int xfpregs_set(struct task_struct *target, const struct user_regset *regset,
const void *kbuf, const void __user *ubuf)
{
struct fpu *fpu = &target->thread.fpu;
- struct user32_fxsr_struct newstate;
+ struct fxregs_state newstate;
int ret;
- BUILD_BUG_ON(sizeof(newstate) != sizeof(struct fxregs_state));
-
if (!cpu_feature_enabled(X86_FEATURE_FXSR))
return -ENODEV;
@@ -116,9 +114,10 @@ int xfpregs_set(struct task_struct *target, const struct user_regset *regset,
/* Copy the state */
memcpy(&fpu->fpstate->regs.fxsave, &newstate, sizeof(newstate));
- /* Clear xmm8..15 */
+ /* Clear xmm8..15 for 32-bit callers */
BUILD_BUG_ON(sizeof(fpu->__fpstate.regs.fxsave.xmm_space) != 16 * 16);
- memset(&fpu->fpstate->regs.fxsave.xmm_space[8], 0, 8 * 16);
+ if (in_ia32_syscall())
+ memset(&fpu->fpstate->regs.fxsave.xmm_space[8*4], 0, 8 * 16);
/* Mark FP and SSE as in use when XSAVE is enabled */
if (use_xsave())
diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index 6d2244c94799..8d2f2f995539 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -1224,7 +1224,7 @@ static struct user_regset x86_64_regsets[] __ro_after_init = {
},
[REGSET_FP] = {
.core_note_type = NT_PRFPREG,
- .n = sizeof(struct user_i387_struct) / sizeof(long),
+ .n = sizeof(struct fxregs_state) / sizeof(long),
.size = sizeof(long), .align = sizeof(long),
.active = regset_xregset_fpregs_active, .regset_get = xfpregs_get, .set = xfpregs_set
},
@@ -1271,7 +1271,7 @@ static struct user_regset x86_32_regsets[] __ro_after_init = {
},
[REGSET_XFP] = {
.core_note_type = NT_PRXFPREG,
- .n = sizeof(struct user32_fxsr_struct) / sizeof(u32),
+ .n = sizeof(struct fxregs_state) / sizeof(u32),
.size = sizeof(u32), .align = sizeof(u32),
.active = regset_xregset_fpregs_active, .regset_get = xfpregs_get, .set = xfpregs_set
},