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 <[email protected]>
Cc: [email protected]
Signed-off-by: Sebastian Ott <[email protected]>
---
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
