linux-kernel - [PATCH] NOMMU: Don't pass NULL pointers to fput() in do_mmap

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:	Fri, 30 Oct 2009 13:13:26 +0000
From:	David Howells <dhowells@...hat.com>
To:	torvalds@...l.org, akpm@...ux-foundation.org
Cc:	linux-kernel@...r.kernel.org, David Howells <dhowells@...hat.com>,
	Robin Getz <rgetz@...ckfin.uclinux.org>
Subject: [PATCH] NOMMU: Don't pass NULL pointers to fput() in do_mmap_pgoff()

Don't pass NULL pointers to fput() in the error handling paths of the NOMMU
do_mmap_pgoff() as it can't handle it.

The following can be used as a test program:

	int main() { static long long a[1024 * 1024 * 20] = { 0 }; return a;}

Without the patch, the code oopses in atomic_long_dec_and_test() as called by
fput() after the kernel complains that it can't allocate that big a chunk of
memory.  With the patch, the kernel just complains about the allocation size
and then the program segfaults during execve() as execve() can't complete the
allocation of all the new ELF program segments.

Reported-by: Robin Getz <rgetz@...ckfin.uclinux.org>
Signed-off-by: David Howells <dhowells@...hat.com>
Acked-by: Robin Getz <rgetz@...ckfin.uclinux.org>
---

 mm/nommu.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)


diff --git a/mm/nommu.c b/mm/nommu.c
index cfea46c..969392c 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -1364,9 +1364,11 @@ share:
 error_just_free:
 	up_write(&nommu_region_sem);
 error:
-	fput(region->vm_file);
+	if (region->vm_file)
+		fput(region->vm_file);
 	kmem_cache_free(vm_region_jar, region);
-	fput(vma->vm_file);
+	if (vma->vm_file)
+		fput(vma->vm_file);
 	if (vma->vm_flags & VM_EXECUTABLE)
 		removed_exe_file_vma(vma->vm_mm);
 	kmem_cache_free(vm_area_cachep, vma);

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/