From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm2-f13.google.com (mail-wm2-f13.google.com [74.125.225.141]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3C334377023 for ; Mon, 21 Sep 2026 19:15:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.225.141 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790018136; cv=none; b=Xu1I9qRqSPaIiXdeVhKxaWy4OghhK0qXR8QHWXL/uQDY+cGU3shI4idQpUE0npg78oXYgOxumDMobGNJ3/lMCqz9sqMk1wmzEEjUY1MN4Bu1FlBJEWM+dWRERT/rwYXwigsy2rGovXyLcQbmZ1DWPczIKPAzT6rtke1skGP7yVo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790018136; c=relaxed/simple; bh=hmrg+XpJNYLDdfEEkchfSyVuGEd3NatTTVR60RLKvr0=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=c4Rq4auWNXiTtyS4+5eRK6l2soVKUD7iIZ1fbtpyM4w+nyxZYu3MBa+AZd30yg5b5vaPGWkx/e1mc5rUrh1zHqDT1choIA2Rq2qYjjB6+eBV57+ToGZ5tWOiFnByEpUeNMT8Jf0JUEshyUu5f4Dp25yeNOJE3O7obo1wszaqbAA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=Ql+gJir5; arc=none smtp.client-ip=74.125.225.141 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Ql+gJir5" Received: by mail-wm2-f13.google.com with SMTP id 5b1f17b1804b1-49e7bcb94d3so23312315e9.2 for ; Mon, 21 Sep 2026 12:15:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1790018133; x=1790622933; darn=lists.linux.dev; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to:content-type; bh=wULW290f2x1A0UN781hUcJJzFUUq+lwGDJV+sTEYl00=; b=Ql+gJir5Xc8qoN5oaKyWW4O3R+EmwJ2RcjpSgmTtPedXjF4nAtsFPD8k3nRnkP1CF4 qAgcU8PgPFDZTEL5OiDIXtrpWt102Mzsz1/vPJjs/uVWtj4oWPEhCirClAda6CPVyz9L apJzQppOnLNgEYZsiETPxr28/bEbX0GTgeAhT/Bd1d0uQWeb3fhFawA0LmGNdIeQVB8v kev+s/Ciq6XsFTedTVQ0/Zj0U8TFtr9aRfLd3+f5StbAEPUEIJIbyqIHld8Yg3K4L8xF H9TDusf5+cKnh0Rz5Z29jAEZsqdyhBr/5HtTJBQqmerVwSKhpcNDX29sgrQPnsGGvCkN p/uA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1790018133; x=1790622933; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to:content-type; bh=wULW290f2x1A0UN781hUcJJzFUUq+lwGDJV+sTEYl00=; b=gV1Dr9U+oGxs5JIBqoACIlFML4GmeaO4Gk4bDbxJvyq4jC9A/jTO6BWcMzdXe7zTmR wIPRFrOxZyyRpqfhARm5HUU8h3zekKRG2beYXFsOL0hpSdyidoziXyaomvPMD/lCzBoR FzQwdzbmxgMuSpBsb2ictF7BmPh9aushCsdX8QmQpnQeWbbOrq84DZFCk6HH0NqvwjR+ wVd9Nicg29QAodrM3MgQDmt6ognu6L6i+hZlV2hoB1iRlVuhSgJbhzzfU1cy+f4rnRJn BC1K3g3POV7/dYPHd5Ra1oH81HW1qQk2Zi7hc04TsDTJiqbFSxEyKXbOe2JxQ1djNxvD Szaw== X-Forwarded-Encrypted: i=1; AKwUvBxketzlnSxwp1I4y/kiyt8Qaeo7IU242ppgSIGmHhSJnoKbUCQggwUa6iDktGg1w/QXQfSIBFW+7Dpa@lists.linux.dev X-Gm-Message-State: AFuF++lsb+x+YGVLh5PEVKEAHY5l6SRqG/oNwkK7HCOteEUMykGQbwFF JaNsf2HRIH0GT0ySOkWBfUqIQwOhGrdq+lUoBCo07MzXFE0qoVxuXi/s X-Gm-Gg: AYBFou1E6HpsxgVA+S0thrSHB0/V52MSFLwV8dDyDqglslLHe01dqGDCwhlnEK7NmCx Rl7whHoreUfAHUVo6v+/UZ/P2CZpyWKHUQaP1iYzGZfsD1vOIgHGMB57RmSWJNth434+2aXb3dm xryeVQlIIhxG0KN3gWtACADPrn9wuNb+jX7STrQyz1l5OPtSPBT3dN4BbGQuqlgzWTco2Uma0As 2XmeoPUJTcnwNUeMISJMDc+F29BPqRzOeEZOWFMiUPvngY74S3hz7Rq5raqY5z0FcERbk8ZrUXc 4iP+U797WltSNpCAPGl/q6BSqQ6yiK6Vcm9MktbFO4qNjDgqXtWkda5x1YB3fQrnyUeSi8ktreU BuNeXYn/6fqhbnXtul8lLKDijCJg+Q2f4gyMeZ3Corgg2QipYFOyFqlVy8T3HpsPKhkMSPdQ4Yo M/Vg+uyZvJMh8GubZL2QNMOoxClOitHV//VhJaDhY7erPbyysO7BqoDlmG0JpDKG5+ew== X-Received: by 2002:a05:600c:a410:b0:49f:d58f:1f8b with SMTP id 5b1f17b1804b1-49fd58f214fmr36767535e9.18.1790018133240; Mon, 21 Sep 2026 12:15:33 -0700 (PDT) Received: from xxxxxx.net ([2a10:8012:d:183:329c:23ff:fe37:f855]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-49fd8cabe7fsm14988155e9.11.2026.09.21.12.15.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 21 Sep 2026 12:15:32 -0700 (PDT) From: Shachar Sharon To: linux-ext4@vger.kernel.org Cc: tytso@mit.edu, fuse-devel@lists.linux.dev, Shachar Sharon Subject: [PATCH] lib/e2p: fix stack smashing on EXT2_IOC_GET/SETVERSION over FUSE Date: Mon, 21 Sep 2026 22:15:23 +0300 Message-ID: <20260921191524.44198-1-synarete@gmail.com> X-Mailer: git-send-email 2.55.0 Precedence: bulk X-Mailing-List: fuse-devel@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit When using utilities like lsattr/chattr on a FUSE backing file-system, invoking the fgetversion or fsetversion functions can result in an abort crash due to "*** stack smashing detected ***". The underlying cause lies in a data structure mismatch between the variable allocation space in user-space and the ioctl encoding expectations defined by Linux: the ioctl command token incorporates the 'long' primitive data size, so the kernel explicitly encodes a 64-bit target memory region pointer when deployed on x86_64. FUSE driver enforce the _IOR-decoded payload envelope, hence it uses 8-byte buffer to accommodate the incoming user-space daemon response. When finalizing the ioctl transaction back down to user space, it writes all 8-bytes directly into the 4-bytes memory reference provided by e2fsprogs. Reproduce: compile with '-fstack-protector-strong' and '-D_FORTIFY_SOURCE=3' (fedor44, 7.2.5-200.fc44.x86_64): $ lsattr -v ./foo *** stack smashing detected ***: terminated Aborted (core dumped) lsattr -v ./foo Solution: change ioctl arg to 'long' but use only lower 32-bits of result. Signed-off-by: Shachar Sharon --- lib/e2p/fgetversion.c | 4 ++-- lib/e2p/fsetversion.c | 7 ++++--- 2 files changed, 6 insertions(+), 5 deletions(-) diff --git a/lib/e2p/fgetversion.c b/lib/e2p/fgetversion.c index f3a5b4cd..eaac46c6 100644 --- a/lib/e2p/fgetversion.c +++ b/lib/e2p/fgetversion.c @@ -45,7 +45,7 @@ int fgetversion(const char *name, unsigned long *version) { - unsigned int ver = -1; + long ver = 0; int rc = -1; #if HAVE_EXT2_IOCTLS # if !APPLE_DARWIN @@ -68,7 +68,7 @@ int fgetversion(const char *name, unsigned long *version) errno = EOPNOTSUPP; #endif /* ! HAVE_EXT2_IOCTLS */ if (rc == 0) - *version = ver; + *version = (unsigned long)ver & 0xffffffffUL; return rc; } diff --git a/lib/e2p/fsetversion.c b/lib/e2p/fsetversion.c index 5f844b55..9b599c19 100644 --- a/lib/e2p/fsetversion.c +++ b/lib/e2p/fsetversion.c @@ -47,12 +47,13 @@ int fsetversion (const char * name, unsigned long version) { #if HAVE_EXT2_IOCTLS #if !APPLE_DARWIN - int fd, r, ver, save_errno = 0; + int fd, r, save_errno = 0; + long ver; fd = open (name, OPEN_FLAGS); if (fd == -1) return -1; - ver = (int) version; + ver = (long) (version & 0xffffffffUL); r = ioctl (fd, EXT2_IOC_SETVERSION, &ver); if (r == -1) save_errno = errno; @@ -61,7 +62,7 @@ int fsetversion (const char * name, unsigned long version) errno = save_errno; return r; #else - int ver = (int)version; + long ver = (long)(version & 0xffffffffUL); return syscall(SYS_fsctl, name, EXT2_IOC_SETVERSION, &ver, 0); #endif #else /* ! HAVE_EXT2_IOCTLS */ -- 2.55.0