tjh.dev / kernel
Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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xen: Make struct privcmd_irqfd's layout architecture independent

Using indirect pointers in an ioctl command argument means that the
layout is architecture specific, in particular we can't use the same one
from 32-bit compat tasks. The general recommendation is to have __u64
members and use u64_to_user_ptr() to access it from the kernel if we are
unable to avoid the pointers altogether.

Fixes: f8941e6c4c71 ("xen: privcmd: Add support for irqfd")
Reported-by: Arnd Bergmann <arnd@kernel.org>
Closes: https://lore.kernel.org/all/268a2031-63b8-4c7d-b1e5-8ab83ca80b4a@app.fastmail.com/
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/a4ef0d4a68fc858b34a81fd3f9877d9b6898eb77.1697439990.git.viresh.kumar@linaro.org
Signed-off-by: Juergen Gross <jgross@suse.com>

authored by

Viresh Kumar and committed by
Juergen Gross 8dd765a5 d3a2b6b4

+2 -2
+1 -1
drivers/xen/privcmd.c
··· 935 935 return -ENOMEM; 936 936 dm_op = kirqfd + 1; 937 937 938 - if (copy_from_user(dm_op, irqfd->dm_op, irqfd->size)) { 938 + if (copy_from_user(dm_op, u64_to_user_ptr(irqfd->dm_op), irqfd->size)) { 939 939 ret = -EFAULT; 940 940 goto error_kfree; 941 941 }
+1 -1
include/uapi/xen/privcmd.h
··· 102 102 #define PRIVCMD_IRQFD_FLAG_DEASSIGN (1 << 0) 103 103 104 104 struct privcmd_irqfd { 105 - void __user *dm_op; 105 + __u64 dm_op; 106 106 __u32 size; /* Size of structure pointed by dm_op */ 107 107 __u32 fd; 108 108 __u32 flags;