The patch titled coredump: pass mm->flags as a coredump parameter for consistency has been added to the -mm tree. Its filename is mm-pass-mm-flags-as-a-coredump-parameter-for-consistency.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: coredump: pass mm->flags as a coredump parameter for consistency From: Masami Hiramatsu <mhiramat@xxxxxxxxxx> Pass mm->flags as a coredump parameter for consistency. --- 1787 if (mm->core_state || !get_dumpable(mm)) { <- (1) 1788 up_write(&mm->mmap_sem); 1789 put_cred(cred); 1790 goto fail; 1791 } 1792 [...] 1798 if (get_dumpable(mm) == 2) { /* Setuid core dump mode */ <-(2) 1799 flag = O_EXCL; /* Stop rewrite attacks */ 1800 cred->fsuid = 0; /* Dump root private */ 1801 } --- Since dumpable bits are not protected by lock, there is a chance to change these bits between (1) and (2). To solve this issue, this patch copies mm->flags to coredump_params.mm_flags at the beginning of do_coredump() and uses it instead of get_dumpable() while dumping core. This copy is also passed to binfmt->core_dump, since elf*_core_dump() uses dump_filter bits in mm->flags. Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx> Acked-by: Roland McGrath <roland@xxxxxxxxxx> Cc: Hidehiro Kawai <hidehiro.kawai.ez@xxxxxxxxxxx> Cc: Oleg Nesterov <oleg@xxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxx> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/binfmt_elf.c | 12 ++---------- fs/binfmt_elf_fdpic.c | 12 ++---------- fs/exec.c | 20 ++++++++++++++++---- include/linux/binfmts.h | 1 + 4 files changed, 21 insertions(+), 24 deletions(-) diff -puN fs/binfmt_elf.c~mm-pass-mm-flags-as-a-coredump-parameter-for-consistency fs/binfmt_elf.c --- a/fs/binfmt_elf.c~mm-pass-mm-flags-as-a-coredump-parameter-for-consistency +++ a/fs/binfmt_elf.c @@ -1911,7 +1911,6 @@ static int elf_core_dump(struct coredump struct vm_area_struct *vma, *gate_vma; struct elfhdr *elf = NULL; loff_t offset = 0, dataoff, foffset; - unsigned long mm_flags; struct elf_note_info info; /* @@ -1976,13 +1975,6 @@ static int elf_core_dump(struct coredump dataoff = offset = roundup(offset, ELF_EXEC_PAGESIZE); - /* - * We must use the same mm->flags while dumping core to avoid - * inconsistency between the program headers and bodies, otherwise an - * unusable core file can be generated. - */ - mm_flags = current->mm->flags; - /* Write program headers for segments dump */ for (vma = first_vma(current, gate_vma); vma != NULL; vma = next_vma(vma, gate_vma)) { @@ -1992,7 +1984,7 @@ static int elf_core_dump(struct coredump phdr.p_offset = offset; phdr.p_vaddr = vma->vm_start; phdr.p_paddr = 0; - phdr.p_filesz = vma_dump_size(vma, mm_flags); + phdr.p_filesz = vma_dump_size(vma, cprm->mm_flags); phdr.p_memsz = vma->vm_end - vma->vm_start; offset += phdr.p_filesz; phdr.p_flags = vma->vm_flags & VM_READ ? PF_R : 0; @@ -2025,7 +2017,7 @@ static int elf_core_dump(struct coredump unsigned long addr; unsigned long end; - end = vma->vm_start + vma_dump_size(vma, mm_flags); + end = vma->vm_start + vma_dump_size(vma, cprm->mm_flags); for (addr = vma->vm_start; addr < end; addr += PAGE_SIZE) { struct page *page; diff -puN fs/binfmt_elf_fdpic.c~mm-pass-mm-flags-as-a-coredump-parameter-for-consistency fs/binfmt_elf_fdpic.c --- a/fs/binfmt_elf_fdpic.c~mm-pass-mm-flags-as-a-coredump-parameter-for-consistency +++ a/fs/binfmt_elf_fdpic.c @@ -1606,7 +1606,6 @@ static int elf_fdpic_core_dump(struct co #endif int thread_status_size = 0; elf_addr_t *auxv; - unsigned long mm_flags; /* * We no longer stop all VM operations. @@ -1737,13 +1736,6 @@ static int elf_fdpic_core_dump(struct co /* Page-align dumped data */ dataoff = offset = roundup(offset, ELF_EXEC_PAGESIZE); - /* - * We must use the same mm->flags while dumping core to avoid - * inconsistency between the program headers and bodies, otherwise an - * unusable core file can be generated. - */ - mm_flags = current->mm->flags; - /* write program headers for segments dump */ for (vma = current->mm->mmap; vma; vma = vma->vm_next) { struct elf_phdr phdr; @@ -1755,7 +1747,7 @@ static int elf_fdpic_core_dump(struct co phdr.p_offset = offset; phdr.p_vaddr = vma->vm_start; phdr.p_paddr = 0; - phdr.p_filesz = maydump(vma, mm_flags) ? sz : 0; + phdr.p_filesz = maydump(vma, cprm->mm_flags) ? sz : 0; phdr.p_memsz = sz; offset += phdr.p_filesz; phdr.p_flags = vma->vm_flags & VM_READ ? PF_R : 0; @@ -1791,7 +1783,7 @@ static int elf_fdpic_core_dump(struct co goto end_coredump; if (elf_fdpic_dump_segments(cprm->file, &size, &cprm->limit, - mm_flags) < 0) + cprm->mm_flags) < 0) goto end_coredump; #ifdef ELF_CORE_WRITE_EXTRA_DATA diff -puN fs/exec.c~mm-pass-mm-flags-as-a-coredump-parameter-for-consistency fs/exec.c --- a/fs/exec.c~mm-pass-mm-flags-as-a-coredump-parameter-for-consistency +++ a/fs/exec.c @@ -1726,14 +1726,19 @@ void set_dumpable(struct mm_struct *mm, } } -int get_dumpable(struct mm_struct *mm) +static int __get_dumpable(unsigned long mm_flags) { int ret; - ret = mm->flags & 0x3; + ret = mm_flags & MMF_DUMPABLE_MASK; return (ret >= 2) ? 2 : ret; } +int get_dumpable(struct mm_struct *mm) +{ + return __get_dumpable(mm->flags); +} + static void wait_for_dump_helpers(struct file *file) { struct pipe_inode_info *pipe; @@ -1777,6 +1782,12 @@ void do_coredump(long signr, int exit_co .signr = signr, .regs = regs, .limit = rlimit(RLIMIT_CORE), + /* + * We must use the same mm->flags while dumping core to avoid + * inconsistency of bit flags, since this flag is not protected + * by any locks. + */ + .mm_flags = mm->flags, }; audit_core_dumps(signr); @@ -1795,7 +1806,7 @@ void do_coredump(long signr, int exit_co /* * If another thread got here first, or we are not dumpable, bail out. */ - if (mm->core_state || !get_dumpable(mm)) { + if (mm->core_state || !__get_dumpable(cprm.mm_flags)) { up_write(&mm->mmap_sem); put_cred(cred); goto fail; @@ -1806,7 +1817,8 @@ void do_coredump(long signr, int exit_co * process nor do we know its entire history. We only know it * was tainted so we dump it as root in mode 2. */ - if (get_dumpable(mm) == 2) { /* Setuid core dump mode */ + if (__get_dumpable(cprm.mm_flags) == 2) { + /* Setuid core dump mode */ flag = O_EXCL; /* Stop rewrite attacks */ cred->fsuid = 0; /* Dump root private */ } diff -puN include/linux/binfmts.h~mm-pass-mm-flags-as-a-coredump-parameter-for-consistency include/linux/binfmts.h --- a/include/linux/binfmts.h~mm-pass-mm-flags-as-a-coredump-parameter-for-consistency +++ a/include/linux/binfmts.h @@ -74,6 +74,7 @@ struct coredump_params { struct pt_regs *regs; struct file *file; unsigned long limit; + unsigned long mm_flags; }; /* _ Patches currently in -mm which might be from mhiramat@xxxxxxxxxx are origin.patch mm-pass-mm-flags-as-a-coredump-parameter-for-consistency.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html