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authorDave Martin <Dave.Martin@arm.com>2017-06-29 15:25:47 +0100
committerWill Deacon <will.deacon@arm.com>2017-06-29 17:44:08 +0100
commit53b1a742ed251780267a57415bc955bd50f40c3d (patch)
treed3f864d5ac31202d46312bf85ae8bea7533b39e6 /arch
parent15ad6ace52039c7e39435c4d712d147126604a97 (diff)
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arm64: ptrace: Avoid setting compat FP[SC]R to garbage if get_user fails
If get_user() fails when reading the new FPSCR value from userspace in compat_vfp_get(), then garbage* will be written to the task's FPSR and FPCR registers. This patch prevents this by checking the return from get_user() first. [*] Actually, zero, due to the behaviour of get_user() on error, but that's still not what userspace expects. Fixes: 478fcb2cdb23 ("arm64: Debugging support") Signed-off-by: Dave Martin <Dave.Martin@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'arch')
-rw-r--r--arch/arm64/kernel/ptrace.c6
1 files changed, 4 insertions, 2 deletions
diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
index 35846f1550db..4c068dcf1977 100644
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -947,8 +947,10 @@ static int compat_vfp_set(struct task_struct *target,
if (count && !ret) {
ret = get_user(fpscr, (compat_ulong_t *)ubuf);
- uregs->fpsr = fpscr & VFP_FPSCR_STAT_MASK;
- uregs->fpcr = fpscr & VFP_FPSCR_CTRL_MASK;
+ if (!ret) {
+ uregs->fpsr = fpscr & VFP_FPSCR_STAT_MASK;
+ uregs->fpcr = fpscr & VFP_FPSCR_CTRL_MASK;
+ }
}
fpsimd_flush_task_state(target);