| From | Greg Kroah-Hartman <> | Subject | [PATCH 5.10 49/95] vfs: check fd has read access in kernel_read_file_from_fd() | Date | Mon, 25 Oct 2021 21:14:46 +0200 |
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From: Matthew Wilcox (Oracle) <willy@infradead.org>
commit 032146cda85566abcd1c4884d9d23e4e30a07e9a upstream.
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> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- fs/kernel_read_file.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/fs/kernel_read_file.c +++ b/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);
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