diff options
| author | Eric W. Biederman <ebiederm@xmission.com> | 2022-03-08 22:04:19 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-04-08 15:24:18 +0300 |
| commit | 39fd0cc079c98dafcf355997ada7b5e67f0bb10a (patch) | |
| tree | a9c5ce6552cf3706117fbb5f999d1968010eee11 /fs/coredump.c | |
| parent | cabd69640957f029b476bc2d74ebf24ac67da6bb (diff) | |
| download | linux-39fd0cc079c98dafcf355997ada7b5e67f0bb10a.tar.xz | |
coredump: Use the vma snapshot in fill_files_note
commit 390031c942116d4733310f0684beb8db19885fe6 upstream.
Matthew Wilcox reported that there is a missing mmap_lock in
file_files_note that could possibly lead to a user after free.
Solve this by using the existing vma snapshot for consistency
and to avoid the need to take the mmap_lock anywhere in the
coredump code except for dump_vma_snapshot.
Update the dump_vma_snapshot to capture vm_pgoff and vm_file
that are neeeded by fill_files_note.
Add free_vma_snapshot to free the captured values of vm_file.
Reported-by: Matthew Wilcox <willy@infradead.org>
Link: https://lkml.kernel.org/r/20220131153740.2396974-1-willy@infradead.org
Cc: stable@vger.kernel.org
Fixes: a07279c9a8cd ("binfmt_elf, binfmt_elf_fdpic: use a VMA list snapshot")
Fixes: 2aa362c49c31 ("coredump: extend core dump note section to contain file names of mapped files")
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs/coredump.c')
| -rw-r--r-- | fs/coredump.c | 22 |
1 files changed, 21 insertions, 1 deletions
diff --git a/fs/coredump.c b/fs/coredump.c index e95fea3beaeb..26eb5a095832 100644 --- a/fs/coredump.c +++ b/fs/coredump.c @@ -54,6 +54,7 @@ #include <trace/events/sched.h> static bool dump_vma_snapshot(struct coredump_params *cprm); +static void free_vma_snapshot(struct coredump_params *cprm); int core_uses_pid; unsigned int core_pipe_limit; @@ -834,7 +835,7 @@ void do_coredump(const kernel_siginfo_t *siginfo) dump_emit(&cprm, "", 1); } file_end_write(cprm.file); - kvfree(cprm.vma_meta); + free_vma_snapshot(&cprm); } if (ispipe && core_pipe_limit) wait_for_dump_helpers(cprm.file); @@ -1111,6 +1112,20 @@ static struct vm_area_struct *next_vma(struct vm_area_struct *this_vma, return gate_vma; } +static void free_vma_snapshot(struct coredump_params *cprm) +{ + if (cprm->vma_meta) { + int i; + for (i = 0; i < cprm->vma_count; i++) { + struct file *file = cprm->vma_meta[i].file; + if (file) + fput(file); + } + kvfree(cprm->vma_meta); + cprm->vma_meta = NULL; + } +} + /* * Under the mmap_lock, take a snapshot of relevant information about the task's * VMAs. @@ -1147,6 +1162,11 @@ static bool dump_vma_snapshot(struct coredump_params *cprm) m->end = vma->vm_end; m->flags = vma->vm_flags; m->dump_size = vma_dump_size(vma, cprm->mm_flags); + m->pgoff = vma->vm_pgoff; + + m->file = vma->vm_file; + if (m->file) + get_file(m->file); } mmap_write_unlock(mm); |