From: Catalin Marinas catalin.marinas@arm.com
commit 4f4c549feb4ecca95ae9abb88887b941d196f83a upstream.
The MTE coredump code in arch/arm64/kernel/elfcore.c iterates over the vma list without the mmap_lock held. This can race with another process or userfaultfd concurrently modifying the vma list. Change the for_each_mte_vma macro and its callers to instead use the vma snapshot taken by dump_vma_snapshot() and stored in the cprm object.
Fixes: 6dd8b1a0b6cb ("arm64: mte: Dump the MTE tags in the core file") Cc: stable@vger.kernel.org # 5.18.x Signed-off-by: Catalin Marinas catalin.marinas@arm.com Reported-by: Seth Jenkins sethjenkins@google.com Suggested-by: Seth Jenkins sethjenkins@google.com Cc: Will Deacon will@kernel.org Link: https://lore.kernel.org/r/20221222181251.1345752-4-catalin.marinas@arm.com Signed-off-by: Will Deacon will@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/arm64/kernel/elfcore.c | 56 ++++++++++++++++++++------------------------ 1 file changed, 26 insertions(+), 30 deletions(-)
--- a/arch/arm64/kernel/elfcore.c +++ b/arch/arm64/kernel/elfcore.c @@ -8,28 +8,27 @@ #include <asm/cpufeature.h> #include <asm/mte.h>
-#define for_each_mte_vma(vmi, vma) \ +#define for_each_mte_vma(cprm, i, m) \ if (system_supports_mte()) \ - for_each_vma(vmi, vma) \ - if (vma->vm_flags & VM_MTE) + for (i = 0, m = cprm->vma_meta; \ + i < cprm->vma_count; \ + i++, m = cprm->vma_meta + i) \ + if (m->flags & VM_MTE)
-static unsigned long mte_vma_tag_dump_size(struct vm_area_struct *vma) +static unsigned long mte_vma_tag_dump_size(struct core_vma_metadata *m) { - if (vma->vm_flags & VM_DONTDUMP) - return 0; - - return vma_pages(vma) * MTE_PAGE_TAG_STORAGE; + return (m->dump_size >> PAGE_SHIFT) * MTE_PAGE_TAG_STORAGE; }
/* Derived from dump_user_range(); start/end must be page-aligned */ static int mte_dump_tag_range(struct coredump_params *cprm, - unsigned long start, unsigned long end) + unsigned long start, unsigned long len) { int ret = 1; unsigned long addr; void *tags = NULL;
- for (addr = start; addr < end; addr += PAGE_SIZE) { + for (addr = start; addr < start + len; addr += PAGE_SIZE) { struct page *page = get_dump_page(addr);
/* @@ -78,11 +77,11 @@ static int mte_dump_tag_range(struct cor
Elf_Half elf_core_extra_phdrs(void) { - struct vm_area_struct *vma; + int i; + struct core_vma_metadata *m; int vma_count = 0; - VMA_ITERATOR(vmi, current->mm, 0);
- for_each_mte_vma(vmi, vma) + for_each_mte_vma(cprm, i, m) vma_count++;
return vma_count; @@ -90,18 +89,18 @@ Elf_Half elf_core_extra_phdrs(void)
int elf_core_write_extra_phdrs(struct coredump_params *cprm, loff_t offset) { - struct vm_area_struct *vma; - VMA_ITERATOR(vmi, current->mm, 0); + int i; + struct core_vma_metadata *m;
- for_each_mte_vma(vmi, vma) { + for_each_mte_vma(cprm, i, m) { struct elf_phdr phdr;
phdr.p_type = PT_AARCH64_MEMTAG_MTE; phdr.p_offset = offset; - phdr.p_vaddr = vma->vm_start; + phdr.p_vaddr = m->start; phdr.p_paddr = 0; - phdr.p_filesz = mte_vma_tag_dump_size(vma); - phdr.p_memsz = vma->vm_end - vma->vm_start; + phdr.p_filesz = mte_vma_tag_dump_size(m); + phdr.p_memsz = m->end - m->start; offset += phdr.p_filesz; phdr.p_flags = 0; phdr.p_align = 0; @@ -115,26 +114,23 @@ int elf_core_write_extra_phdrs(struct co
size_t elf_core_extra_data_size(void) { - struct vm_area_struct *vma; + int i; + struct core_vma_metadata *m; size_t data_size = 0; - VMA_ITERATOR(vmi, current->mm, 0);
- for_each_mte_vma(vmi, vma) - data_size += mte_vma_tag_dump_size(vma); + for_each_mte_vma(cprm, i, m) + data_size += mte_vma_tag_dump_size(m);
return data_size; }
int elf_core_write_extra_data(struct coredump_params *cprm) { - struct vm_area_struct *vma; - VMA_ITERATOR(vmi, current->mm, 0); - - for_each_mte_vma(vmi, vma) { - if (vma->vm_flags & VM_DONTDUMP) - continue; + int i; + struct core_vma_metadata *m;
- if (!mte_dump_tag_range(cprm, vma->vm_start, vma->vm_end)) + for_each_mte_vma(cprm, i, m) { + if (!mte_dump_tag_range(cprm, m->start, m->dump_size)) return 0; }