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commit b72bbba23687ed67887d1d18c51cce5cc9c575ca
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Author: Siddhesh Poyarekar <siddhesh@sourceware.org>
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Date: Fri May 13 10:01:47 2022 +0530
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fortify: Ensure that __glibc_fortify condition is a constant [BZ #29141]
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The fix c8ee1c85 introduced a -1 check for object size without also
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checking that object size is a constant. Because of this, the tree
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optimizer passes in gcc fail to fold away one of the branches in
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__glibc_fortify and trips on a spurious Wstringop-overflow. The warning
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itself is incorrect and the branch does go away eventually in DCE in the
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rtl passes in gcc, but the constant check is a helpful hint to simplify
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code early, so add it in.
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Resolves: BZ #29141
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Signed-off-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
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(cherry picked from commit 61a87530108ec9181e1b18a9b727ec3cc3ba7532)
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diff --git a/misc/sys/cdefs.h b/misc/sys/cdefs.h
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index b36013b9a6b4d9c3..e0ecd9147ee3ce48 100644
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--- a/misc/sys/cdefs.h
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+++ b/misc/sys/cdefs.h
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@@ -163,7 +163,7 @@
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/* Length is known to be safe at compile time if the __L * __S <= __OBJSZ
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condition can be folded to a constant and if it is true, or unknown (-1) */
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#define __glibc_safe_or_unknown_len(__l, __s, __osz) \
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- ((__osz) == (__SIZE_TYPE__) -1 \
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+ ((__builtin_constant_p (__osz) && (__osz) == (__SIZE_TYPE__) -1) \
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|| (__glibc_unsigned_or_positive (__l) \
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&& __builtin_constant_p (__glibc_safe_len_cond ((__SIZE_TYPE__) (__l), \
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(__s), (__osz))) \
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