Hi Kees
On 2020-07-10 3:44 p.m., Kees Cook wrote:
On Fri, Jul 10, 2020 at 03:10:25PM -0700, Scott Branden wrote:
On 2020-07-10 3:04 p.m., Matthew Wilcox wrote:
On Fri, Jul 10, 2020 at 02:00:32PM -0700, Scott Branden wrote:
@@ -950,8 +951,8 @@ int kernel_read_file(struct file *file, void **buf, loff_t *size,
goto out;
}
- if (id != READING_FIRMWARE_PREALLOC_BUFFER)
- *buf = vmalloc(i_size);
+ if (!*buf)
The assumption that *buf is always NULL when id !=
READING_FIRMWARE_PREALLOC_BUFFER doesn't appear to be correct.
I get unhandled page faults due to this change on boot.
Did it give you a stack backtrace?
Yes, but there's no requirement that *buf need to be NULL when calling this
function.
To fix my particular crash I added the following locally:
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -3989,7 +3989,7 @@ SYSCALL_DEFINE3(finit_module, int, fd, const char
__user *, uargs, int, flags)
{
struct load_info info = { };
loff_t size;
- void *hdr;
+ void *hdr = NULL;
int err;
err = may_init_module();
Thanks for the diagnosis and fix! I haven't had time to cycle back
around to this series yet. Hopefully soon. :)
In order to assist in your patchset I have combined it with my patch
series here:
https://github.com/sbranden/linux/tree/kernel_read_file_for_kees
Please let me know if this matches your expectations for my patches or
if there is something else I need to change.
Thanks,
Scott
