From 93eb211e6c9ff6054fcf9c5b9e344d8d9ad29175 Mon Sep 17 00:00:00 2001 From: Daisuke HATAYAMA Date: Fri, 5 Mar 2010 13:44:09 -0800 Subject: [PATCH] elf coredump: make offset calculation process and writing process explicit By the next patch, elf_core_dump() and elf_fdpic_core_dump() will support extended numbering and so will produce the corefiles with section header table in a special case. The problem is the process of writing a file header offset of the section header table into e_shoff field of the ELF header. ELF header is positioned at the beginning of the corefile, while section header at the end. So, we need to take which of the following ways: 1. Seek backward to retry writing operation for ELF header after writing process for a whole part 2. Make offset calculation process and writing process totally sequential The clause 1. is not always possible: one cannot assume that file system supports seek function. Consider the no_llseek case. Therefore, this patch adopts the clause 2. Signed-off-by: Daisuke HATAYAMA Cc: "Luck, Tony" Cc: Jeff Dike Cc: David Howells Cc: Greg Ungerer Cc: Roland McGrath Cc: Oleg Nesterov Cc: Ingo Molnar Cc: Alexander Viro Cc: Andi Kleen Cc: Alan Cox Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/binfmt_elf.c | 27 ++++++++++++++++----------- fs/binfmt_elf_fdpic.c | 29 ++++++++++++++++------------- 2 files changed, 32 insertions(+), 24 deletions(-) diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c index c1a499599b7d..6fc49b6ed936 100644 --- a/fs/binfmt_elf.c +++ b/fs/binfmt_elf.c @@ -1856,6 +1856,7 @@ static int elf_core_dump(struct coredump_params *cprm) loff_t offset = 0, dataoff, foffset; unsigned long mm_flags; struct elf_note_info info; + struct elf_phdr *phdr4note = NULL; /* * We no longer stop all VM operations. @@ -1898,28 +1899,22 @@ static int elf_core_dump(struct coredump_params *cprm) fs = get_fs(); set_fs(KERNEL_DS); - size += sizeof(*elf); - if (size > cprm->limit || !dump_write(cprm->file, elf, sizeof(*elf))) - goto end_coredump; - offset += sizeof(*elf); /* Elf header */ offset += (segs + 1) * sizeof(struct elf_phdr); /* Program headers */ foffset = offset; /* Write notes phdr entry */ { - struct elf_phdr phdr; size_t sz = get_note_info_size(&info); sz += elf_coredump_extra_notes_size(); - fill_elf_note_phdr(&phdr, sz, offset); - offset += sz; - - size += sizeof(phdr); - if (size > cprm->limit - || !dump_write(cprm->file, &phdr, sizeof(phdr))) + phdr4note = kmalloc(sizeof(*phdr4note), GFP_KERNEL); + if (!phdr4note) goto end_coredump; + + fill_elf_note_phdr(phdr4note, sz, offset); + offset += sz; } dataoff = offset = roundup(offset, ELF_EXEC_PAGESIZE); @@ -1931,6 +1926,15 @@ static int elf_core_dump(struct coredump_params *cprm) */ mm_flags = current->mm->flags; + size += sizeof(*elf); + if (size > cprm->limit || !dump_write(cprm->file, elf, sizeof(*elf))) + goto end_coredump; + + size += sizeof(*phdr4note); + if (size > cprm->limit + || !dump_write(cprm->file, phdr4note, sizeof(*phdr4note))) + goto end_coredump; + /* Write program headers for segments dump */ for (vma = first_vma(current, gate_vma); vma != NULL; vma = next_vma(vma, gate_vma)) { @@ -2004,6 +2008,7 @@ end_coredump: cleanup: free_note_info(&info); + kfree(phdr4note); kfree(elf); out: return has_dumped; diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c index 952699a86ec3..112da491d75d 100644 --- a/fs/binfmt_elf_fdpic.c +++ b/fs/binfmt_elf_fdpic.c @@ -1600,6 +1600,7 @@ static int elf_fdpic_core_dump(struct coredump_params *cprm) int thread_status_size = 0; elf_addr_t *auxv; unsigned long mm_flags; + struct elf_phdr *phdr4note = NULL; /* * We no longer stop all VM operations. @@ -1706,18 +1707,12 @@ static int elf_fdpic_core_dump(struct coredump_params *cprm) fs = get_fs(); set_fs(KERNEL_DS); - size += sizeof(*elf); - if (size > cprm->limit - || !dump_write(cprm->file, elf, sizeof(*elf))) - goto end_coredump; - offset += sizeof(*elf); /* Elf header */ offset += (segs+1) * sizeof(struct elf_phdr); /* Program headers */ foffset = offset; /* Write notes phdr entry */ { - struct elf_phdr phdr; int sz = 0; for (i = 0; i < numnote; i++) @@ -1725,13 +1720,12 @@ static int elf_fdpic_core_dump(struct coredump_params *cprm) sz += thread_status_size; - fill_elf_note_phdr(&phdr, sz, offset); - offset += sz; - - size += sizeof(phdr); - if (size > cprm->limit - || !dump_write(cprm->file, &phdr, sizeof(phdr))) + phdr4note = kmalloc(sizeof(*phdr4note), GFP_KERNEL); + if (!phdr4note) goto end_coredump; + + fill_elf_note_phdr(phdr4note, sz, offset); + offset += sz; } /* Page-align dumped data */ @@ -1744,6 +1738,15 @@ static int elf_fdpic_core_dump(struct coredump_params *cprm) */ mm_flags = current->mm->flags; + size += sizeof(*elf); + if (size > cprm->limit || !dump_write(cprm->file, elf, sizeof(*elf))) + goto end_coredump; + + size += sizeof(*phdr4note); + if (size > cprm->limit + || !dump_write(cprm->file, phdr4note, sizeof(*phdr4note))) + goto end_coredump; + /* write program headers for segments dump */ for (vma = current->mm->mmap; vma; vma = vma->vm_next) { struct elf_phdr phdr; @@ -1815,7 +1818,7 @@ cleanup: list_del(tmp); kfree(list_entry(tmp, struct elf_thread_status, list)); } - + kfree(phdr4note); kfree(elf); kfree(prstatus); kfree(psinfo); -- 2.20.1