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| author | Matthew Wilcox (Oracle) <willy@infradead.org> | 2021-10-18 15:16:12 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2021-10-18 20:22:03 -1000 |
| commit | 032146cda85566abcd1c4884d9d23e4e30a07e9a (patch) | |
| tree | 94db8693ba1de0ac9090a2eb235071ae7ef7a98c /fs | |
| parent | b0e901280d9860a0a35055f220e8e457f300f40a (diff) | |
| download | lwn-032146cda85566abcd1c4884d9d23e4e30a07e9a.tar.gz lwn-032146cda85566abcd1c4884d9d23e4e30a07e9a.zip | |
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>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/kernel_read_file.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/kernel_read_file.c b/fs/kernel_read_file.c index 87aac4c72c37..1b07550485b9 100644 --- a/fs/kernel_read_file.c +++ b/fs/kernel_read_file.c @@ -178,7 +178,7 @@ int kernel_read_file_from_fd(int fd, loff_t offset, void **buf, 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); |