Re: [PATCH] cxl: Fix null pointer dereference in cxl_get_fd

[Frederic Barrat]

On 04/12/2023 03:07, Kunwu Chan wrote:

kasprintf() returns a pointer to dynamically allocated memory
which can be NULL upon failure.

Fixes: bdecf76e319a ("cxl: Fix coredump generation when cxl_get_fd() is used")
Signed-off-by: Kunwu Chan <chen...@kylinos.cn>
---
  drivers/misc/cxl/api.c | 4 ++++
  1 file changed, 4 insertions(+)

diff --git a/drivers/misc/cxl/api.c b/drivers/misc/cxl/api.c
index d85c56530863..bfd7ccd4d7e1 100644
--- a/drivers/misc/cxl/api.c
+++ b/drivers/misc/cxl/api.c
@@ -419,6 +419,10 @@ struct file *cxl_get_fd(struct cxl_context *ctx, struct 
file_operations *fops,
                fops = (struct file_operations *)&afu_fops;

name = kasprintf(GFP_KERNEL, "cxl:%d", ctx->pe);

+       if (!name) {
+               put_unused_fd(fdtmp);
+               return ERR_PTR(-ENOMEM);
+       }

That works, but you might as well follow the existing error path:

        name = kasprintf(GFP_KERNEL, "cxl:%d", ctx->pe);
        if (!name)
                goto err_fd;

  Fred

        file = cxl_getfile(name, fops, ctx, flags);
        kfree(name);
        if (IS_ERR(file))