path: root/lib
diff options
authorStephen Boyd <sboyd@codeaurora.org>2013-04-30 15:28:42 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-04-30 17:04:09 -0700
commit446f24d1199e8a546ba7c97da3fbb9a505a94795 (patch)
tree42c44a565fbdd6f923e0c2403b1c62154acab1b2 /lib
parenta05342cbd62b7f6dacb8d71683d799f5e5e694b8 (diff)
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>
Diffstat (limited to 'lib')
3 files changed, 28 insertions, 0 deletions
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 77ebaa3dfa12..770a422a42e8 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -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.
+ bool
+ bool "Strict user copy size checks"
+ 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
diff --git a/lib/Makefile b/lib/Makefile
index 23c9a0fe74fc..e9c52e1b853a 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -15,6 +15,7 @@ lib-y := ctype.o string.o vsprintf.o cmdline.o \
is_single_threaded.o plist.o decompress.o kobject_uevent.o \
lib-$(CONFIG_MMU) += ioremap.o
lib-$(CONFIG_SMP) += cpumask.o
diff --git a/lib/usercopy.c b/lib/usercopy.c
new file mode 100644
index 000000000000..4f5b1ddbcd25
--- /dev/null
+++ b/lib/usercopy.c
@@ -0,0 +1,9 @@
+#include <linux/export.h>
+#include <linux/bug.h>
+#include <linux/uaccess.h>
+void copy_from_user_overflow(void)
+ WARN(1, "Buffer overflow detected!\n");

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