Hello Kees, On Thu, 28 Sep 2023, Kees Cook wrote:
This is the continuation of the work Eric started for handling "p_memsz > p_filesz" in arbitrary segments (rather than just the last, BSS, segment). I've added the suggested changes: - drop unused "elf_bss" variable - refactor load_elf_interp() to use elf_load() - refactor load_elf_library() to use elf_load() - report padzero() errors when PROT_WRITE is present - drop vm_brk()
While I was debugging the initial issue I stumbled over the following - care to take it as part of this series? ----->8 [PATCH] mm: vm_brk_flags don't bail out while holding lock Calling vm_brk_flags() with flags set other than VM_EXEC will exit the function without releasing the mmap_write_lock. Just do the sanity check before the lock is acquired. This doesn't fix an actual issue since no caller sets a flag other than VM_EXEC. Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: linux-mm@xxxxxxxxx Signed-off-by: Sebastian Ott <sebott@xxxxxxxxxx> --- mm/mmap.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/mm/mmap.c b/mm/mmap.c index b56a7f0c9f85..7ed286662839 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -3143,13 +3143,13 @@ int vm_brk_flags(unsigned long addr, unsigned long request, unsigned long flags) if (!len) return 0; - if (mmap_write_lock_killable(mm)) - return -EINTR; - /* Until we need other flags, refuse anything except VM_EXEC. */ if ((flags & (~VM_EXEC)) != 0) return -EINVAL; + if (mmap_write_lock_killable(mm)) + return -EINTR; + ret = check_brk_limits(addr, len); if (ret) goto limits_failed; -- 2.41.0
