Messages in this thread Patch in this message | | | Date | Sun, 06 Jun 2021 01:47:49 +0200 | From | Thomas Gleixner <> | Subject | [patch V2 07/14] x86/fpu: Add address range checks to copy_user_to_xstate() |
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From: Andy Lutomirski <luto@kernel.org>
copy_user_to_xstate() uses __copy_from_user(), which provides a negligible speedup. Fortunately, both call sites are at least almost correct. __fpu__restore_sig() checks access_ok() with a length of xstate_sigframe_size() and ptrace regset access uses fpu_user_xstate_size. These should be valid upper bounds on the length, so, at worst, this would cause spurious failures and not accesses to kernel memory.
Nonetheless, this is far more fragile than necessary and none of these callers are in a hotpath.
Use copy_from_user() instead.
Signed-off-by: Andy Lutomirski <luto@kernel.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> --- arch/x86/kernel/fpu/xstate.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
--- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -1192,7 +1192,7 @@ int copy_user_to_xstate(struct xregs_sta offset = offsetof(struct xregs_state, header); size = sizeof(hdr); - if (__copy_from_user(&hdr, ubuf + offset, size)) + if (copy_from_user(&hdr, ubuf + offset, size)) return -EFAULT; if (validate_user_xstate_header(&hdr)) @@ -1207,7 +1207,7 @@ int copy_user_to_xstate(struct xregs_sta offset = xstate_offsets[i]; size = xstate_sizes[i]; - if (__copy_from_user(dst, ubuf + offset, size)) + if (copy_from_user(dst, ubuf + offset, size)) return -EFAULT; } } @@ -1215,7 +1215,7 @@ int copy_user_to_xstate(struct xregs_sta if (xfeatures_mxcsr_quirk(hdr.xfeatures)) { offset = offsetof(struct fxregs_state, mxcsr); size = MXCSR_AND_FLAGS_SIZE; - if (__copy_from_user(&xsave->i387.mxcsr, ubuf + offset, size)) + if (copy_from_user(&xsave->i387.mxcsr, ubuf + offset, size)) return -EFAULT; }
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