From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 38BEAD68BCA for ; Thu, 18 Dec 2025 00:59:03 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 8ED7B6B0088; Wed, 17 Dec 2025 19:59:02 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 8A51F6B0089; Wed, 17 Dec 2025 19:59:02 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 7F8596B008A; Wed, 17 Dec 2025 19:59:02 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 6D2DA6B0088 for ; Wed, 17 Dec 2025 19:59:02 -0500 (EST) Received: from smtpin02.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id EF6751609AA for ; Thu, 18 Dec 2025 00:59:01 +0000 (UTC) X-FDA: 84230782482.02.A52D15F Received: from out-179.mta1.migadu.com (out-179.mta1.migadu.com [95.215.58.179]) by imf15.hostedemail.com (Postfix) with ESMTP id 0BFFFA0008 for ; Thu, 18 Dec 2025 00:58:59 +0000 (UTC) Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b="m/yKrYt5"; spf=pass (imf15.hostedemail.com: domain of shakeel.butt@linux.dev designates 95.215.58.179 as permitted sender) smtp.mailfrom=shakeel.butt@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1766019540; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:references:dkim-signature; bh=FLWdrmcOXEsn7JZI2AfrrHLsKmuHiuoeH/04si3RGkU=; b=JY/tvo2xVENy6P+iEIJ6oYPuwuQmvF8IECb9QuFTdXkUM2kpC/diwuUcNFJ49rVQv7s0aF 0s/yQ99sq92RA96YhgzfH01IdpEhvw45WaB9cufJV625azqoqKgog7HbDWErGmRhaD1tu6 G7UbIUPfkGGsSRg2rhMCpSfgGN/n9wk= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1766019540; a=rsa-sha256; cv=none; b=qK/SBQ9U5wewiYibCoCU09GpInWv19uQU5T7Gag+cUFWjdEnuLFetDCocOikbjod2ikNvD XAb8PNeoXNQWWnDCCNBePK2wZJ2U8/kmKGGv9bnJFUpjVUD1pVaZN2C5nTdwGSyEtpGGjv wo6VuUiPCa8tsO62vvp7zNi3J/TLaqQ= ARC-Authentication-Results: i=1; imf15.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b="m/yKrYt5"; spf=pass (imf15.hostedemail.com: domain of shakeel.butt@linux.dev designates 95.215.58.179 as permitted sender) smtp.mailfrom=shakeel.butt@linux.dev; dmarc=pass (policy=none) header.from=linux.dev X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1766019537; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=FLWdrmcOXEsn7JZI2AfrrHLsKmuHiuoeH/04si3RGkU=; b=m/yKrYt5HoWNtJeA+j0Hu6aLAMgMu5AjYG/IguQGaktUvPC9JVFLH5YTW/m41v4Hw1xukx +aY+Y1OcgfnlcYm7X4kxfHQ8JEeRiheY9gAK4XdGIq8wJsz/y+03u4JQdkVV61P4CctyzD thnzVrGb6eGQf7nMKPFxWbONYzedpgY= From: Shakeel Butt To: Andrew Morton , Matthew Wilcox , Andrii Nakryiko Cc: Shaurya Rane , "Darrick J . Wong" , Christoph Hellwig , Alexei Starovoitov , Daniel Borkmann , Meta kernel team , bpf@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, syzbot+09b7d050e4806540153d@syzkaller.appspotmail.com Subject: [PATCH] lib/buildid: use __kernel_read() for sleepable context Date: Wed, 17 Dec 2025 16:58:18 -0800 Message-ID: <20251218005818.614819-1-shakeel.butt@linux.dev> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Stat-Signature: 374f5i4oyn4hbotpg4xqq8xm7mac1rd7 X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 0BFFFA0008 X-Rspam-User: X-HE-Tag: 1766019539-852294 X-HE-Meta: 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 TN7HwrjY Txo9TNMBRkhqioGtAiCrMy5R4a35EbwB6DwXPRWOTIYO+vgYkC1/sudECa/z+Bt853x0rKVcWRAEOccVcHBR5gFOlKWvXbpdDzASnJprq/Os31uI4FFqJw8fYCUv2EhthUZts43vJwbjQvfWYi1B9xsyYnWl6dn32zt0rwa141aPz2tb/aLEIi/eM1ViiaW3LwNNkVbeGXfCMa26iXu7MkQai6VxSBIuHfnCuJs3qXihSdOB94Hl5T2hKThInYYAMTY/Lgc1fQoz3qCZE8kihsN2VVMjuiZ2AEQxna90jaw50k5rxExdGTsdXNbbQLgICagE/Zglz798LZaFTqQF39IcuYGYAFndFMfKOZhdX62w3mPf2RKPkYsvwNqmh+TFdnlVt0zovifz7bQuZf+R4FhMcaPQxkxJMobj3fa39PW+qwbHBf9JhLOHqnYi377PZBCYInezR3fZt9oZRbhEdNAeNag== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: For the sleepable context, convert freader to use __kernel_read() instead of direct page cache access via read_cache_folio(). This simplifies the faultable code path by using the standard kernel file reading interface which handles all the complexity of reading file data. At the moment we are not changing the code for non-sleepable context which uses filemap_get_folio() and only succeeds if the target folios are already in memory and up-to-date. The reason is to keep the patch simple and easier to backport to stable kernels. Syzbot repro does not crash the kernel anymore and the selftests run successfully. In the follow up we will make __kernel_read() with IOCB_NOWAIT work for non-sleepable contexts. In addition, I would like to replace the secretmem check with a more generic approach and will add fstest for the buildid code. Reported-by: syzbot+09b7d050e4806540153d@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=09b7d050e4806540153d Fixes: ad41251c290d ("lib/buildid: implement sleepable build_id_parse() API") Signed-off-by: Shakeel Butt --- lib/buildid.c | 47 +++++++++++++++++++++++++++++++++++------------ 1 file changed, 35 insertions(+), 12 deletions(-) diff --git a/lib/buildid.c b/lib/buildid.c index aaf61dfc0919..e7e258532720 100644 --- a/lib/buildid.c +++ b/lib/buildid.c @@ -5,6 +5,7 @@ #include #include #include +#include #include #define BUILD_ID 3 @@ -37,6 +38,29 @@ static void freader_put_folio(struct freader *r) r->folio = NULL; } +/* + * Data is read directly into r->buf. Returns pointer to the buffer + * on success, NULL on failure with r->err set. + */ +static const void *freader_fetch_sync(struct freader *r, loff_t file_off, size_t sz) +{ + ssize_t ret; + loff_t pos = file_off; + char *buf = r->buf; + + do { + ret = __kernel_read(r->file, r->buf, sz, &pos); + if (ret <= 0) { + r->err = ret ?: -EIO; + return NULL; + } + buf += ret; + sz -= ret; + } while (sz > 0); + + return r->buf; +} + static int freader_get_folio(struct freader *r, loff_t file_off) { /* check if we can just reuse current folio */ @@ -46,20 +70,9 @@ static int freader_get_folio(struct freader *r, loff_t file_off) freader_put_folio(r); - /* reject secretmem folios created with memfd_secret() */ - if (secretmem_mapping(r->file->f_mapping)) - return -EFAULT; - + /* only use page cache lookup - fail if not already cached */ r->folio = filemap_get_folio(r->file->f_mapping, file_off >> PAGE_SHIFT); - /* if sleeping is allowed, wait for the page, if necessary */ - if (r->may_fault && (IS_ERR(r->folio) || !folio_test_uptodate(r->folio))) { - filemap_invalidate_lock_shared(r->file->f_mapping); - r->folio = read_cache_folio(r->file->f_mapping, file_off >> PAGE_SHIFT, - NULL, r->file); - filemap_invalidate_unlock_shared(r->file->f_mapping); - } - if (IS_ERR(r->folio) || !folio_test_uptodate(r->folio)) { if (!IS_ERR(r->folio)) folio_put(r->folio); @@ -97,6 +110,16 @@ const void *freader_fetch(struct freader *r, loff_t file_off, size_t sz) return r->data + file_off; } + /* reject secretmem folios created with memfd_secret() */ + if (secretmem_mapping(r->file->f_mapping)) { + r->err = -EFAULT; + return NULL; + } + + /* use __kernel_read() for sleepable context */ + if (r->may_fault) + return freader_fetch_sync(r, file_off, sz); + /* fetch or reuse folio for given file offset */ r->err = freader_get_folio(r, file_off); if (r->err) -- 2.47.3