| Message ID | 20210727205855.411487-32-keescook@chromium.org (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | Introduce strict memcpy() bounds checking | expand |
| Context | Check | Description |
|---|---|---|
| netdev/tree_selection | success | Guessing tree name failed - patch did not apply |
On 7/27/2021 1:58 PM, Kees Cook wrote: > Clang has never correctly compiled the FORTIFY_SOURCE defenses due to > a couple bugs: > > Eliding inlines with matching __builtin_* names > https://bugs.llvm.org/show_bug.cgi?id=50322 > > Incorrect __builtin_constant_p() of some globals > https://bugs.llvm.org/show_bug.cgi?id=41459 > > In the process of making improvements to the FORTIFY_SOURCE defenses, the > first (silent) bug (coincidentally) becomes worked around, but exposes > the latter which breaks the build. As such, Clang must not be used with > CONFIG_FORTIFY_SOURCE until at least latter bug is fixed (in Clang 13), > and the fortify routines have been rearranged. > > Update the Kconfig to reflect the reality of the current situation. > > Signed-off-by: Kees Cook <keescook@chromium.org> > --- > security/Kconfig | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/security/Kconfig b/security/Kconfig > index 0ced7fd33e4d..8f0e675e70a4 100644 > --- a/security/Kconfig > +++ b/security/Kconfig > @@ -191,6 +191,9 @@ config HARDENED_USERCOPY_PAGESPAN > config FORTIFY_SOURCE > bool "Harden common str/mem functions against buffer overflows" > depends on ARCH_HAS_FORTIFY_SOURCE > + # https://bugs.llvm.org/show_bug.cgi?id=50322 > + # https://bugs.llvm.org/show_bug.cgi?id=41459 > + depends on !CONFIG_CC_IS_CLANG Should be !CC_IS_CLANG, Kconfig is hard :) > help > Detect overflows of buffers in common string and memory functions > where the compiler can determine and validate the buffer sizes. > Cheers, Nathan
On Tue, Jul 27, 2021 at 02:18:58PM -0700, Nathan Chancellor wrote: > On 7/27/2021 1:58 PM, Kees Cook wrote: > > Clang has never correctly compiled the FORTIFY_SOURCE defenses due to > > a couple bugs: > > > > Eliding inlines with matching __builtin_* names > > https://bugs.llvm.org/show_bug.cgi?id=50322 > > > > Incorrect __builtin_constant_p() of some globals > > https://bugs.llvm.org/show_bug.cgi?id=41459 > > > > In the process of making improvements to the FORTIFY_SOURCE defenses, the > > first (silent) bug (coincidentally) becomes worked around, but exposes > > the latter which breaks the build. As such, Clang must not be used with > > CONFIG_FORTIFY_SOURCE until at least latter bug is fixed (in Clang 13), > > and the fortify routines have been rearranged. > > > > Update the Kconfig to reflect the reality of the current situation. > > > > Signed-off-by: Kees Cook <keescook@chromium.org> > > --- > > security/Kconfig | 3 +++ > > 1 file changed, 3 insertions(+) > > > > diff --git a/security/Kconfig b/security/Kconfig > > index 0ced7fd33e4d..8f0e675e70a4 100644 > > --- a/security/Kconfig > > +++ b/security/Kconfig > > @@ -191,6 +191,9 @@ config HARDENED_USERCOPY_PAGESPAN > > config FORTIFY_SOURCE > > bool "Harden common str/mem functions against buffer overflows" > > depends on ARCH_HAS_FORTIFY_SOURCE > > + # https://bugs.llvm.org/show_bug.cgi?id=50322 > > + # https://bugs.llvm.org/show_bug.cgi?id=41459 > > + depends on !CONFIG_CC_IS_CLANG > > Should be !CC_IS_CLANG, Kconfig is hard :) /me shakes fist at sky Thank you! Fixed locally. :) -Kees > > > help > > Detect overflows of buffers in common string and memory functions > > where the compiler can determine and validate the buffer sizes. > > > > Cheers, > Nathan
diff --git a/security/Kconfig b/security/Kconfig index 0ced7fd33e4d..8f0e675e70a4 100644 --- a/security/Kconfig +++ b/security/Kconfig @@ -191,6 +191,9 @@ config HARDENED_USERCOPY_PAGESPAN config FORTIFY_SOURCE bool "Harden common str/mem functions against buffer overflows" depends on ARCH_HAS_FORTIFY_SOURCE + # https://bugs.llvm.org/show_bug.cgi?id=50322 + # https://bugs.llvm.org/show_bug.cgi?id=41459 + depends on !CONFIG_CC_IS_CLANG help Detect overflows of buffers in common string and memory functions where the compiler can determine and validate the buffer sizes.
Clang has never correctly compiled the FORTIFY_SOURCE defenses due to a couple bugs: Eliding inlines with matching __builtin_* names https://bugs.llvm.org/show_bug.cgi?id=50322 Incorrect __builtin_constant_p() of some globals https://bugs.llvm.org/show_bug.cgi?id=41459 In the process of making improvements to the FORTIFY_SOURCE defenses, the first (silent) bug (coincidentally) becomes worked around, but exposes the latter which breaks the build. As such, Clang must not be used with CONFIG_FORTIFY_SOURCE until at least latter bug is fixed (in Clang 13), and the fortify routines have been rearranged. Update the Kconfig to reflect the reality of the current situation. Signed-off-by: Kees Cook <keescook@chromium.org> --- security/Kconfig | 3 +++ 1 file changed, 3 insertions(+)