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Commit 032146cd authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle) Committed by Linus Torvalds
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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: b844f0ec ("vfs: define kernel_copy_file_from_fd()")
Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Reported-by: default avatarHao Sun <sunhao.th@gmail.com>
Reviewed-by: default avatarKees Cook <keescook@chromium.org>
Acked-by: default avatarChristian 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent b0e90128
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