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authorMatthew Wilcox (Oracle) <willy@infradead.org>2021-10-19 01:16:12 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2021-10-19 09:22:03 +0300
commit032146cda85566abcd1c4884d9d23e4e30a07e9a (patch)
tree94db8693ba1de0ac9090a2eb235071ae7ef7a98c /fs/kernel_read_file.c
parentb0e901280d9860a0a35055f220e8e457f300f40a (diff)
downloadlinux-032146cda85566abcd1c4884d9d23e4e30a07e9a.tar.xz
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/kernel_read_file.c')
-rw-r--r--fs/kernel_read_file.c2
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);