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authorEric W. Biederman <ebiederm@xmission.com>2017-08-17 17:07:46 -0500
committerEric W. Biederman <ebiederm@xmission.com>2018-01-12 14:21:05 -0600
commit7771c66457004977b616bab785209f49d164f527 (patch)
treeb7677fb8c299b3333934e8879c7f1e2c3fb68da0 /arch
parent526c3ddb6aa270fe6f71d227eac1e189746cc257 (diff)
downloadlinux-7771c66457004977b616bab785209f49d164f527.tar.bz2
signal/arm: Document conflicts with SI_USER and SIGFPE
Setting si_code to 0 results in a userspace seeing an si_code of 0. This is the same si_code as SI_USER. Posix and common sense requires that SI_USER not be a signal specific si_code. As such this use of 0 for the si_code is a pretty horribly broken ABI. Further use of si_code == 0 guaranteed that copy_siginfo_to_user saw a value of __SI_KILL and now sees a value of SIL_KILL with the result that uid and pid fields are copied and which might copying the si_addr field by accident but certainly not by design. Making this a very flakey implementation. Utilizing FPE_FIXME, siginfo_layout will now return SIL_FAULT and the appropriate fields will be reliably copied. Possible ABI fixes includee: - Send the signal without siginfo - Don't generate a signal - Possibly assign and use an appropriate si_code - Don't handle cases which can't happen Cc: Russell King <rmk@flint.arm.linux.org.uk> Cc: linux-arm-kernel@lists.infradead.org Ref: 451436b7bbb2 ("[ARM] Add support code for ARM hardware vector floating point") History Tree: https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Diffstat (limited to 'arch')
-rw-r--r--arch/arm/include/uapi/asm/siginfo.h13
-rw-r--r--arch/arm/vfp/vfpmodule.c2
2 files changed, 14 insertions, 1 deletions
diff --git a/arch/arm/include/uapi/asm/siginfo.h b/arch/arm/include/uapi/asm/siginfo.h
new file mode 100644
index 000000000000..d0513880be21
--- /dev/null
+++ b/arch/arm/include/uapi/asm/siginfo.h
@@ -0,0 +1,13 @@
+#ifndef __ASM_SIGINFO_H
+#define __ASM_SIGINFO_H
+
+#include <asm-generic/siginfo.h>
+
+/*
+ * SIGFPE si_codes
+ */
+#ifdef __KERNEL__
+#define FPE_FIXME 0 /* Broken dup of SI_USER */
+#endif /* __KERNEL__ */
+
+#endif
diff --git a/arch/arm/vfp/vfpmodule.c b/arch/arm/vfp/vfpmodule.c
index a71a48e71fff..03c6a3c72f9c 100644
--- a/arch/arm/vfp/vfpmodule.c
+++ b/arch/arm/vfp/vfpmodule.c
@@ -257,7 +257,7 @@ static void vfp_raise_exceptions(u32 exceptions, u32 inst, u32 fpscr, struct pt_
if (exceptions == VFP_EXCEPTION_ERROR) {
vfp_panic("unhandled bounce", inst);
- vfp_raise_sigfpe(0, regs);
+ vfp_raise_sigfpe(FPE_FIXME, regs);
return;
}