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Kconfig: consolidate CONFIG_DEBUG_STRICT_USER_COPY_CHECKS

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The help text for this config is duplicated across the x86, parisc, and
s390 Kconfig.debug files.  Arnd Bergman noted that the help text was
slightly misleading and should be fixed to state that enabling this
option isn't a problem when using pre 4.4 gcc.

To simplify the rewording, consolidate the text into lib/Kconfig.debug
and modify it there to be more explicit about when you should say N to
this config.

Also, make the text a bit more generic by stating that this option
enables compile time checks so we can cover architectures which emit
warnings vs.  ones which emit errors.  The details of how an
architecture decided to implement the checks isn't as important as the
concept of compile time checking of copy_from_user() calls.

While we're doing this, remove all the copy_from_user_overflow() code
that's duplicated many times and place it into lib/ so that any
architecture supporting this option can get the function for free.

Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Ingo Molnar <mingo@kernel.org>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Acked-by: Helge Deller <deller@gmx.de>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Stephen Boyd
2013-04-30 15:28:42 -07:00
committed by Linus Torvalds
parent a05342cbd6
commit 446f24d119
16 changed files with 31 additions and 76 deletions
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lib/Kconfig.debug
+18
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@@ -1292,6 +1292,24 @@ config LATENCYTOP
Enable this option if you want to use the LatencyTOP tool
to find out which userspace is blocking on what kernel operations.
config ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
bool
config DEBUG_STRICT_USER_COPY_CHECKS
bool "Strict user copy size checks"
depends on ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
depends on DEBUG_KERNEL && !TRACE_BRANCH_PROFILING
help
Enabling this option turns a certain set of sanity checks for user
copy operations into compile time failures.
The copy_from_user() etc checks are there to help test if there
are sufficient security checks on the length argument of
the copy operation, by having gcc prove that the argument is
within bounds.
If unsure, say N.
source mm/Kconfig.debug
source kernel/trace/Kconfig