From 30415f6a63f3383a18e9adf7c144acabe6893f63 Mon Sep 17 00:00:00 2001 From: Michael Ellerman Date: Thu, 3 Nov 2005 21:10:48 +1100 Subject: [PATCH] powerpc: Fix random memory corruption in merged elf.h The merged verison of ELF_CORE_COPY_REGS is basically the PPC64 version, with a memset that came from PPC and a few types abstracted out into #defines. But it's not _quite_ right. The first problem is we calculate the number of registers with: nregs = sizeof(struct pt_regs) / sizeof(ELF_GREG_TYPE) For a 32-bit process on a 64-bit kernel that's bogus because the registers are 64 bits, but ELF_GREG_TYPE is u32, so nregs == 88 which is wrong. The other problem is the memset, which assumes a struct pt_regs is smaller than a struct elf_regs. For a 32-bit process on a 64-bit kernel that's false. The fix is to calculate the number of regs using sizeof(unsigned long), which should always be right, and just memset the whole damn thing _before_ copying the registers in. Signed-off-by: Michael Ellerman --- include/asm-powerpc/elf.h | 22 +++++++++++++--------- 1 file changed, 13 insertions(+), 9 deletions(-) diff --git a/include/asm-powerpc/elf.h b/include/asm-powerpc/elf.h index d22b10021b5d..d140577d0a05 100644 --- a/include/asm-powerpc/elf.h +++ b/include/asm-powerpc/elf.h @@ -178,18 +178,22 @@ typedef elf_vrreg_t elf_vrregset_t32[ELF_NVRREG32]; static inline void ppc_elf_core_copy_regs(elf_gregset_t elf_regs, struct pt_regs *regs) { - int i; - int gprs = sizeof(struct pt_regs)/sizeof(ELF_GREG_TYPE); + int i, nregs; - if (gprs > ELF_NGREG) - gprs = ELF_NGREG; + memset((void *)elf_regs, 0, sizeof(elf_gregset_t)); - for (i=0; i < gprs; i++) - elf_regs[i] = (elf_greg_t)((ELF_GREG_TYPE *)regs)[i]; - - memset((char *)(elf_regs) + sizeof(struct pt_regs), 0, \ - sizeof(elf_gregset_t) - sizeof(struct pt_regs)); + /* Our registers are always unsigned longs, whether we're a 32 bit + * process or 64 bit, on either a 64 bit or 32 bit kernel. + * Don't use ELF_GREG_TYPE here. */ + nregs = sizeof(struct pt_regs) / sizeof(unsigned long); + if (nregs > ELF_NGREG) + nregs = ELF_NGREG; + for (i = 0; i < nregs; i++) { + /* This will correctly truncate 64 bit registers to 32 bits + * for a 32 bit process on a 64 bit kernel. */ + elf_regs[i] = (elf_greg_t)((ELF_GREG_TYPE *)regs)[i]; + } } #define ELF_CORE_COPY_REGS(gregs, regs) ppc_elf_core_copy_regs(gregs, regs); -- 2.20.1