tree a0a5eeb436a297dffead2dfbccbb0ad3013aa7d1
parent b925585039cf39275c2e0e57512e5df27fa73aad
author H. Peter Anvin <hpa@zytor.com> 1260575303 -0800
committer H. Peter Anvin <hpa@zytor.com> 1260575303 -0800

nvram: Fix write beyond end condition; prove to gcc copy is safe

In nvram_write, first of all, correctly handle the case where the file
pointer is already beyond the end; we should return EOF in that case.

Second, make the logic a bit more explicit so that gcc can statically
prove that the copy_from_user() is safe.  Once the condition of the
beyond-end filepointer is eliminated, the copy is safe but gcc can't
prove it, causing build failures for i386 allyesconfig.

Third, eliminate the entirely superfluous variable "len", and just use
the passed-in variable "count" instead.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Wim Van Sebroeck <wim@iguana.be>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <tip-*@git.kernel.org>