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.
Reported-by: Hao Sun <sunhao.th@xxxxxxxxx>
Fixes: b844f0ecbc56 ("vfs: define kernel_copy_file_from_fd()")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
---
fs/kernel_read_file.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
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);
--
2.32.0
