From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id 813333836E80; Tue, 28 Nov 2023 17:29:30 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 813333836E80 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1701192570; bh=L3LN074P14cRbzXIOjC5wIebe8kT6Rpa2OlFxDkUJfQ=; h=From:To:Subject:Date:In-Reply-To:References:From; b=KP64v9n42GgqQ0xzLvbqNQ5DFRUU++Ossl2VMK7c+1e+IAbdR21dGRFb74R6DWkvb 33g8UUMGnyWpdDr+u5REY7Wpd9i1m3QWYbWu8Otlf5H9znR7jFT9ko5P5JW4eiy6IF 5gmsBVZxAkOpbHlqzJsx4x2OQRwIUe8NldvmNJ4o= From: "cvs-commit at gcc dot gnu.org" To: glibc-bugs@sourceware.org Subject: [Bug dynamic-link/29039] Corrupt DTV after reuse of a TLS module ID following dlclose with unused TLS Date: Tue, 28 Nov 2023 17:29:28 +0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: glibc X-Bugzilla-Component: dynamic-link X-Bugzilla-Version: 2.35 X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: cvs-commit at gcc dot gnu.org X-Bugzilla-Status: UNCONFIRMED X-Bugzilla-Resolution: X-Bugzilla-Priority: P2 X-Bugzilla-Assigned-To: unassigned at sourceware dot org X-Bugzilla-Target-Milestone: --- X-Bugzilla-Flags: security- X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: http://sourceware.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 List-Id: https://sourceware.org/bugzilla/show_bug.cgi?id=3D29039 --- Comment #4 from Sourceware Commits --- The master branch has been updated by Szabolcs Nagy : https://sourceware.org/git/gitweb.cgi?p=3Dglibc.git;h=3D3921c5b40f293c57cb3= 26f58713c924b0662ef59 commit 3921c5b40f293c57cb326f58713c924b0662ef59 Author: Hector Martin Date: Tue Nov 28 15:23:07 2023 +0900 elf: Fix TLS modid reuse generation assignment (BZ 29039) _dl_assign_tls_modid() assigns a slotinfo entry for a new module, but does *not* do anything to the generation counter. The first time this happens, the generation is zero and map_generation() returns the current generation to be used during relocation processing. However, if a slotinfo entry is later reused, it will already have a generation assigned. If this generation has fallen behind the current global max generation, then this causes an obsolete generation to be assigned during relocation processing, as map_generation() returns this generation if nonzero. _dl_add_to_slotinfo() eventually resets the generation, but by then it is too late. This causes DTV updates to be skipped, leading to NULL or broken TLS slot pointers and segfaults. Fix this by resetting the generation to zero in _dl_assign_tls_modid(), so it behaves the same as the first time a slot is assigned. _dl_add_to_slotinfo() will still assign the correct static generation later during module load, but relocation processing will no longer use an obsolete generation. Note that slotinfo entry (aka modid) reuse typically happens after a dlclose and only TLS access via dynamic tlsdesc is affected. Because tlsdesc is optimized to use the optional part of static TLS, dynamic tlsdesc can be avoided by increasing the glibc.rtld.optional_static_tls tunable to a large enough value, or by LD_PRELOAD-ing the affected modules. Fixes bug 29039. Reviewed-by: Szabolcs Nagy --=20 You are receiving this mail because: You are on the CC list for the bug.=