diff options
| -rw-r--r-- | fs/coredump.c | 39 |
1 files changed, 34 insertions, 5 deletions
diff --git a/fs/coredump.c b/fs/coredump.c index 1c060c0a2d72..b73817712dd2 100644 --- a/fs/coredump.c +++ b/fs/coredump.c @@ -42,6 +42,7 @@ #include <linux/path.h> #include <linux/timekeeping.h> #include <linux/sysctl.h> +#include <linux/elf.h> #include <linux/uaccess.h> #include <asm/mmu_context.h> @@ -980,6 +981,8 @@ static bool always_dump_vma(struct vm_area_struct *vma) return false; } +#define DUMP_SIZE_MAYBE_ELFHDR_PLACEHOLDER 1 + /* * Decide how much of @vma's contents should be included in a core dump. */ @@ -1039,9 +1042,20 @@ static unsigned long vma_dump_size(struct vm_area_struct *vma, * dump the first page to aid in determining what was mapped here. */ if (FILTER(ELF_HEADERS) && - vma->vm_pgoff == 0 && (vma->vm_flags & VM_READ) && - (READ_ONCE(file_inode(vma->vm_file)->i_mode) & 0111) != 0) - return PAGE_SIZE; + vma->vm_pgoff == 0 && (vma->vm_flags & VM_READ)) { + if ((READ_ONCE(file_inode(vma->vm_file)->i_mode) & 0111) != 0) + return PAGE_SIZE; + + /* + * ELF libraries aren't always executable. + * We'll want to check whether the mapping starts with the ELF + * magic, but not now - we're holding the mmap lock, + * so copy_from_user() doesn't work here. + * Use a placeholder instead, and fix it up later in + * dump_vma_snapshot(). + */ + return DUMP_SIZE_MAYBE_ELFHDR_PLACEHOLDER; + } #undef FILTER @@ -1116,8 +1130,6 @@ int dump_vma_snapshot(struct coredump_params *cprm, int *vma_count, m->end = vma->vm_end; m->flags = vma->vm_flags; m->dump_size = vma_dump_size(vma, cprm->mm_flags); - - vma_data_size += m->dump_size; } mmap_write_unlock(mm); @@ -1127,6 +1139,23 @@ int dump_vma_snapshot(struct coredump_params *cprm, int *vma_count, return -EFAULT; } + for (i = 0; i < *vma_count; i++) { + struct core_vma_metadata *m = (*vma_meta) + i; + + if (m->dump_size == DUMP_SIZE_MAYBE_ELFHDR_PLACEHOLDER) { + char elfmag[SELFMAG]; + + if (copy_from_user(elfmag, (void __user *)m->start, SELFMAG) || + memcmp(elfmag, ELFMAG, SELFMAG) != 0) { + m->dump_size = 0; + } else { + m->dump_size = PAGE_SIZE; + } + } + + vma_data_size += m->dump_size; + } + *vma_data_size_ptr = vma_data_size; return 0; } |