[RFC PATCH v1 3/9] x86/umip: Be stricter in fixup_umip_exception()

"Christophe Leroy (CS GROUP)" <[email protected]> Mon, 27 Apr 2026 19:13:44 +0200
Newsgroups gmane.comp.freedesktop.xorg.drivers.intel,gmane.linux.ports.alpha,gmane.linux.kernel,gmane.linux.kernel.arc,gmane.linux.ports.arm.kernel,gmane.linux.ports.mips,gmane.linux.ports.ppc64.devel,gmane.comp.emulators.kvm.devel,gmane.linux.ports.riscv,gmane.linux.ports.sparc,gmane.linux.uml.devel,gmane.linux.kernel.efi,gmane.comp.freedesktop.amd-gfx,gmane.comp.video.dri.devel,gmane.linux.network,gmane.linux.kernel.wireless.general,gmane.linux.kernel.spi.devel,gmane.linux.drivers.video-input-infrastructure,gmane.linux.serial,gmane.linux.usb.general,gmane.comp.emulators.xen.devel,gmane.linux.file-systems,gmane.linux.kernel.bpf,gmane.linux.kernel.mm,gmane.linux.x25,gmane.linux.kernel.rust,gmane.linux.sound,gmane.linux.ports.hexagon,gmane.linux.ports.parisc,gmane.linux.ports.sh.devel,gmane.linux.kernel.cross-arch
Message-ID <9e8e43d4f81d8f8b6f68311f1c6f859d718d36e4.1777306795.git.chleroy@kernel.org>
fixup_umip_exception() calls copy_to_user() and checks whether
the returned value is strictly positive.

A subsequent patch will change the return of copy_to_user() to
return -EFAULT in case of error.

Change the test to checking that the result is not 0.

At the time being copy_to_user() return an unsigned value so
'strictly positive' is the same as 'not 0'.

Signed-off-by: Christophe Leroy (CS GROUP) <[email protected]>
---
 arch/x86/kernel/umip.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/umip.c b/arch/x86/kernel/umip.c
index 3ce99cbcf187..dfff28ea1dea 100644
--- a/arch/x86/kernel/umip.c
+++ b/arch/x86/kernel/umip.c
@@ -409,7 +409,7 @@ bool fixup_umip_exception(struct pt_regs *regs)
 			return false;
 
 		nr_copied = copy_to_user(uaddr, dummy_data, dummy_data_size);
-		if (nr_copied  > 0) {
+		if (nr_copied) {
 			/*
 			 * If copy fails, send a signal and tell caller that
 			 * fault was fixed up.
-- 
2.49.0