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From: Andrew Morton <akpm@linux-foundation.org>
To: akpm@linux-foundation.org, christian.brauner@ubuntu.com,
	keescook@chromium.org, linux-mm@kvack.org,
	mm-commits@vger.kernel.org, stable@vger.kernel.org,
	sunhao.th@gmail.com, torvalds@linux-foundation.org,
	viro@zeniv.linux.org.uk, willy@infradead.org,
	zohar@linux.ibm.com
Subject: [patch 16/19] vfs: check fd has read access in kernel_read_file_from_fd()
Date: Mon, 18 Oct 2021 15:16:12 -0700	[thread overview]
Message-ID: <20211018221612.hYn1e83d3%akpm@linux-foundation.org> (raw)
In-Reply-To: <20211018151438.f2246e2656c041b6753a8bdd@linux-foundation.org>

From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Subject: vfs: check fd has read access in kernel_read_file_from_fd()

If we open a file without read access and then pass the fd to a syscall
whose implementation calls kernel_read_file_from_fd(), we get a warning
from __kernel_read():

        if (WARN_ON_ONCE(!(file->f_mode & FMODE_READ)))

This currently affects both finit_module() and kexec_file_load(), but it
could affect other syscalls in the future.

Link: https://lkml.kernel.org/r/20211007220110.600005-1-willy@infradead.org
Fixes: b844f0ecbc56 ("vfs: define kernel_copy_file_from_fd()")
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reported-by: Hao Sun <sunhao.th@gmail.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Mimi Zohar <zohar@linux.ibm.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 fs/kernel_read_file.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/fs/kernel_read_file.c~vfs-check-fd-has-read-access-in-kernel_read_file_from_fd
+++ a/fs/kernel_read_file.c
@@ -178,7 +178,7 @@ int kernel_read_file_from_fd(int fd, lof
 	struct fd f = fdget(fd);
 	int ret = -EBADF;
 
-	if (!f.file)
+	if (!f.file || !(f.file->f_mode & FMODE_READ))
 		goto out;
 
 	ret = kernel_read_file(f.file, offset, buf, buf_size, file_size, id);
_


  parent reply	other threads:[~2021-10-18 22:16 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-18 22:14 incoming Andrew Morton
2021-10-18 22:15 ` [patch 01/19] mm/userfaultfd: selftests: fix memory corruption with thp enabled Andrew Morton
2021-10-18 22:15 ` [patch 02/19] userfaultfd: fix a race between writeprotect and exit_mmap() Andrew Morton
2021-10-18 22:15 ` [patch 03/19] mm/migrate: optimize hotplug-time demotion order updates Andrew Morton
2021-10-18 22:15 ` [patch 04/19] mm/migrate: add CPU hotplug to demotion #ifdef Andrew Morton
2021-10-18 22:15 ` [patch 05/19] mm/migrate: fix CPUHP state to update node demotion order Andrew Morton
2021-10-18 22:15 ` [patch 06/19] ocfs2: fix data corruption after conversion from inline format Andrew Morton
2021-10-18 22:15 ` [patch 07/19] ocfs2: mount fails with buffer overflow in strlen Andrew Morton
2021-10-18 22:15 ` [patch 08/19] memblock: check memory total_size Andrew Morton
2021-10-18 22:15 ` [patch 09/19] mm/mempolicy: do not allow illegal MPOL_F_NUMA_BALANCING | MPOL_LOCAL in mbind() Andrew Morton
2021-10-18 22:15 ` [patch 10/19] mm, slub: fix two bugs in slab_debug_trace_open() Andrew Morton
2021-10-18 22:15 ` [patch 11/19] mm, slub: fix mismatch between reconstructed freelist depth and cnt Andrew Morton
2021-10-18 22:15 ` [patch 12/19] mm, slub: fix potential memoryleak in kmem_cache_open() Andrew Morton
2021-10-18 22:16 ` [patch 13/19] mm, slub: fix potential use-after-free in slab_debugfs_fops Andrew Morton
2021-10-18 22:16 ` [patch 14/19] mm, slub: fix incorrect memcg slab count for bulk free Andrew Morton
2021-10-18 22:16 ` [patch 15/19] elfcore: correct reference to CONFIG_UML Andrew Morton
2021-10-18 22:16 ` Andrew Morton [this message]
2021-10-18 22:16 ` [patch 17/19] mm/secretmem: fix NULL page->mapping dereference in page_is_secretmem() Andrew Morton
2021-10-18 22:16 ` [patch 18/19] mm/thp: decrease nr_thps in file's mapping on THP split Andrew Morton
2021-10-18 22:16 ` [patch 19/19] mailmap: add Andrej Shadura Andrew Morton

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