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From: Siddhesh Poyarekar <siddhesh@sourceware.org> To: glibc-cvs@sourceware.org Subject: [glibc/release/2.35/master] fortify: Ensure that __glibc_fortify condition is a constant [BZ #29141] Date: Mon, 16 May 2022 16:24:20 +0000 (GMT) [thread overview] Message-ID: <20220516162420.CCF6D383543F@sourceware.org> (raw) https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=58947e1fa593cff7b5513d5e8e0c81b0131984b4 commit 58947e1fa593cff7b5513d5e8e0c81b0131984b4 Author: Siddhesh Poyarekar <siddhesh@sourceware.org> Date: Fri May 13 10:01:47 2022 +0530 fortify: Ensure that __glibc_fortify condition is a constant [BZ #29141] The fix c8ee1c85 introduced a -1 check for object size without also checking that object size is a constant. Because of this, the tree optimizer passes in gcc fail to fold away one of the branches in __glibc_fortify and trips on a spurious Wstringop-overflow. The warning itself is incorrect and the branch does go away eventually in DCE in the rtl passes in gcc, but the constant check is a helpful hint to simplify code early, so add it in. Resolves: BZ #29141 Signed-off-by: Siddhesh Poyarekar <siddhesh@sourceware.org> Diff: --- misc/sys/cdefs.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/misc/sys/cdefs.h b/misc/sys/cdefs.h index f1faf8292c..1c2b044a0d 100644 --- a/misc/sys/cdefs.h +++ b/misc/sys/cdefs.h @@ -164,7 +164,7 @@ /* Length is known to be safe at compile time if the __L * __S <= __OBJSZ condition can be folded to a constant and if it is true, or unknown (-1) */ #define __glibc_safe_or_unknown_len(__l, __s, __osz) \ - ((__osz) == (__SIZE_TYPE__) -1 \ + ((__builtin_constant_p (__osz) && (__osz) == (__SIZE_TYPE__) -1) \ || (__glibc_unsigned_or_positive (__l) \ && __builtin_constant_p (__glibc_safe_len_cond ((__SIZE_TYPE__) (__l), \ (__s), (__osz))) \
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