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([2600:1700:6476:1430:b801:b375:5db3:9ec3]) by smtp.gmail.com with ESMTPSA id 00721157ae682-896c948db95sm2794047b3.13.2026.09.17.12.35.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 17 Sep 2026 12:35:55 -0700 (PDT) Message-ID: Subject: Re: [PATCH v2] nilfs2: validate segment number in nilfs_sufile_get_suinfo() From: Viacheslav Dubeyko To: Ryusuke Konishi Cc: Aldo Ariel Panzardo , linux-nilfs@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Date: Thu, 17 Sep 2026 12:35:53 -0700 In-Reply-To: References: <20260915195223.3331909-1-qwe.aldo@gmail.com> <8eef80c6c8d21e863c5a3721b1ae681fc4ccf54f.camel@dubeyko.com> Autocrypt: addr=slava@dubeyko.com; prefer-encrypt=mutual; keydata=mQINBGgaTLYBEADaJc/WqWTeunGetXyyGJ5Za7b23M/ozuDCWCp+yWUa2GqQKH40dxRIR zshgOmAue7t9RQJU9lxZ4ZHWbi1Hzz85+0omefEdAKFmxTO6+CYV0g/sapU0wPJws3sC2Pbda9/eJ ZcvScAX2n/PlhpTnzJKf3JkHh3nM1ACO3jzSe2/muSQJvqMLG2D71ccekr1RyUh8V+OZdrPtfkDam V6GOT6IvyE+d+55fzmo20nJKecvbyvdikWwZvjjCENsG9qOf3TcCJ9DDYwjyYe1To8b+mQM9nHcxp jUsUuH074BhISFwt99/htZdSgp4csiGeXr8f9BEotRB6+kjMBHaiJ6B7BIlDmlffyR4f3oR/5hxgy dvIxMocqyc03xVyM6tA4ZrshKkwDgZIFEKkx37ec22ZJczNwGywKQW2TGXUTZVbdooiG4tXbRBLxe ga/NTZ52ZdEkSxAUGw/l0y0InTtdDIWvfUT+WXtQcEPRBE6HHhoeFehLzWL/o7w5Hog+0hXhNjqte fzKpI2fWmYzoIb6ueNmE/8sP9fWXo6Av9m8B5hRvF/hVWfEysr/2LSqN+xjt9NEbg8WNRMLy/Y0MS p5fgf9pmGF78waFiBvgZIQNuQnHrM+0BmYOhR0JKoHjt7r5wLyNiKFc8b7xXndyCDYfniO3ljbr0j tXWRGxx4to6FwARAQABtCZWaWFjaGVzbGF2IER1YmV5a28gPHNsYXZhQGR1YmV5a28uY29tPokCVw QTAQoAQQIbAQUJA8JnAAULCQgHAgYVCgkICwIEFgIDAQIeAQIXgBYhBFXDC2tnzsoLQtrbBDlc2cL fhEB1BQJoGl5PAhkBAAoJEDlc2cLfhEB17DsP/jy/Dx19MtxWOniPqpQf2s65enkDZuMIQ94jSg7B F2qTKIbNR9SmsczjyjC+/J7m7WZRmcqnwFYMOyNfh12aF2WhjT7p5xEAbvfGVYwUpUrg/lcacdT0D Yk61GGc5ZB89OAWHLr0FJjI54bd7kn7E/JRQF4dqNsxU8qcPXQ0wLHxTHUPZu/w5Zu/cO+lQ3H0Pj pSEGaTAh+tBYGSvQ4YPYBcV8+qjTxzeNwkw4ARza8EjTwWKP2jWAfA/ay4VobRfqNQ2zLoo84qDtN Uxe0zPE2wobIXELWkbuW/6hoQFPpMlJWz+mbvVms57NAA1HO8F5c1SLFaJ6dN0AQbxrHi45/cQXla 9hSEOJjxcEnJG/ZmcomYHFneM9K1p1K6HcGajiY2BFWkVet9vuHygkLWXVYZ0lr1paLFR52S7T+cf 6dkxOqu1ZiRegvFoyzBUzlLh/elgp3tWUfG2VmJD3lGpB3m5ZhwQ3rFpK8A7cKzgKjwPp61Me0o9z HX53THoG+QG+o0nnIKK7M8+coToTSyznYoq9C3eKeM/J97x9+h9tbizaeUQvWzQOgG8myUJ5u5Dr4 6tv9KXrOJy0iy/dcyreMYV5lwODaFfOeA4Lbnn5vRn9OjuMg1PFhCi3yMI4lA4umXFw0V2/OI5rgW BQELhfvW6mxkihkl6KLZX8m1zcHitCpWaWFjaGVzbGF2IER1YmV5a28gPFNsYXZhLkR1YmV5a29Aa WJtLmNvbT6JAlQEEwEKAD4WIQRVwwtrZ87KC0La2wQ5XNnC34RAdQUCaBpd7AIbAQUJA8JnAAULCQ gHAgYVCgkICwIEFgIDAQIeAQIXgAAKCRA5XNnC34RAdYjFEACiWBEybMt1xjRbEgaZ3UP5i2bSway DwYDvgWW5EbRP7JcqOcZ2vkJwrK3gsqC3FKpjOPh7ecE0I4vrabH1Qobe2N8B2Y396z24mGnkTBbb 16Uz3PC93nFN1BA0wuOjlr1/oOTy5gBY563vybhnXPfSEUcXRd28jI7z8tRyzXh2tL8ZLdv1u4vQ8 E0O7lVJ55p9yGxbwgb5vXU4T2irqRKLxRvU80rZIXoEM7zLf5r7RaRxgwjTKdu6rYMUOfoyEQQZTD 4Xg9YE/X8pZzcbYFs4IlscyK6cXU0pjwr2ssjearOLLDJ7ygvfOiOuCZL+6zHRunLwq2JH/RmwuLV mWWSbgosZD6c5+wu6DxV15y7zZaR3NFPOR5ErpCFUorKzBO1nA4dwOAbNym9OGkhRgLAyxwpea0V0 ZlStfp0kfVaSZYo7PXd8Bbtyjali0niBjPpEVZdgtVUpBlPr97jBYZ+L5GF3hd6WJFbEYgj+5Af7C UjbX9DHweGQ/tdXWRnJHRzorxzjOS3003ddRnPtQDDN3Z/XzdAZwQAs0RqqXrTeeJrLppFUbAP+HZ TyOLVJcAAlVQROoq8PbM3ZKIaOygjj6Yw0emJi1D9OsN2UKjoe4W185vamFWX4Ba41jmCPrYJWAWH fAMjjkInIPg7RLGs8FiwxfcpkILP0YbVWHiNAabQoVmlhY2hlc2xhdiBEdWJleWtvIDx2ZHViZXlr b0BrZXJuZWwub3JnPokCVAQTAQoAPhYhBFXDC2tnzsoLQtrbBDlc2cLfhEB1BQJoVemuAhsBBQkDw mcABQsJCAcCBhUKCQgLAgQWAgMBAh4BAheAAAoJEDlc2cLfhEB1GRwP/1scX5HO9Sk7dRicLD/fxo ipwEs+UbeA0/TM8OQfdRI4C/tFBYbQCR7lD05dfq8VsYLEyrgeLqP/iRhabLky8LTaEdwoAqPDc/O 9HRffx/faJZqkKc1dZryjqS6b8NExhKOVWmDqN357+Cl/H4hT9wnvjCj1YEqXIxSd/2Pc8+yw/KRC AP7jtRzXHcc/49Lpz/NU5irScusxy2GLKa5o/13jFK3F1fWX1wsOJF8NlTx3rLtBy4GWHITwkBmu8 zI4qcJGp7eudI0l4xmIKKQWanEhVdzBm5UnfyLIa7gQ2T48UbxJlWnMhLxMPrxgtC4Kos1G3zovEy Ep+fJN7D1pwN9aR36jVKvRsX7V4leIDWGzCdfw1FGWkMUfrRwgIl6i3wgqcCP6r9YSWVQYXdmwdMu 1RFLC44iF9340S0hw9+30yGP8TWwd1mm8V/+zsdDAFAoAwisi5QLLkQnEsJSgLzJ9daAsE8KjMthv hUWHdpiUSjyCpigT+KPl9YunZhyrC1jZXERCDPCQVYgaPt+Xbhdjcem/ykv8UVIDAGVXjuk4OW8la nf8SP+uxkTTDKcPHOa5rYRaeNj7T/NClRSd4z6aV3F6pKEJnEGvv/DFMXtSHlbylhyiGKN2Amd0b4 9jg+DW85oNN7q2UYzYuPwkHsFFq5iyF1QggiwYYTpoVXsw Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.60.1 (by Flathub.org) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Fri, 2026-09-18 at 01:05 +0900, Ryusuke Konishi wrote: > On Fri, Sep 18, 2026 at 12:46=E2=80=AFAM Ryusuke Konishi=C2=A0 wrote: > >=20 > > On Thu, Sep 17, 2026 at 4:06=E2=80=AFAM Viacheslav Dubeyko wrote: > > >=20 > > > On Tue, 2026-09-15 at 16:52 -0300, Aldo Ariel Panzardo wrote: > > > > nilfs_sufile_get_suinfo() subtracts the caller-provided segment > > > > number > > > > from the total number of segments without first checking its > > > > range. > > > > If > > > > the requested number is greater than the total, the unsigned > > > > subtraction > > > > wraps and the function may process segment numbers outside the > > > > filesystem. > > > >=20 > > > > Cache the total while holding the metadata semaphore and return > > > > no > > > > entries > > > > when the starting segment number is at or beyond the end. > > > >=20 > > > > Fixes: 6c98cd4ecb0a ("nilfs2: segment usage file") > > > > Cc: stable@vger.kernel.org > > > > Signed-off-by: Aldo Ariel Panzardo > > > > --- > > > > =C2=A0fs/nilfs2/sufile.c | 10 +++++++--- > > > > =C2=A01 file changed, 7 insertions(+), 3 deletions(-) > > > >=20 > > > > diff --git a/fs/nilfs2/sufile.c b/fs/nilfs2/sufile.c > > > > index eceedca026..573646c5f7 100644 > > > > --- a/fs/nilfs2/sufile.c > > > > +++ b/fs/nilfs2/sufile.c > > > > @@ -870,10 +870,14 @@ ssize_t nilfs_sufile_get_suinfo(struct > > > > inode > > > > *sufile, __u64 segnum, void *buf, > > > >=20 > > > > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 down_read(&NILFS_MDT(sufile)->mi_sem= ); > > > >=20 > > > > +=C2=A0=C2=A0=C2=A0=C2=A0 nsegs =3D nilfs_sufile_get_nsegments(sufi= le); > > > > +=C2=A0=C2=A0=C2=A0=C2=A0 if (segnum >=3D nsegs) { > > > > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0 ret =3D 0; > > > > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0 goto out; > > > > +=C2=A0=C2=A0=C2=A0=C2=A0 } > > > > + > > > > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 segusages_per_block =3D > > > > nilfs_sufile_segment_usages_per_block(sufile); > > > > -=C2=A0=C2=A0=C2=A0=C2=A0 nsegs =3D min_t(unsigned long, > > > > -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 nilfs_sufile_get_nsegments(sufil= e) - > > > > segnum, > > > > -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 nsi); > > > > +=C2=A0=C2=A0=C2=A0=C2=A0 nsegs =3D min_t(unsigned long, nsegs - se= gnum, nsi); > > > > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 for (i =3D 0; i < nsegs; i +=3D n, s= egnum +=3D n) { > > > > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0 n =3D min_t(unsigned long, > > > > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 se= gusages_per_block - > > >=20 > > > Looks good to me. > > >=20 > > > Reviewed-by: Viacheslav Dubeyko > > >=20 > > > Thanks, > > > Slava. > >=20 > > Acked-by: Ryusuke Konishi > >=20 > > Hi Viacheslav, > >=20 > > Please take this directly. > >=20 > > I also agree that this change makes sense, and my local test > > results > > are as expected. > >=20 > > However, please drop the 'Cc: stable' tag since it does not cause > > any > > fatal issues at the moment. > > If a real-world problem is found or reported, I think it would be > > fine > > to request a manual backport then. > >=20 > > While acquiring information on out-of-range segments due to > > wrap-around is indeed possible, sufile is also a metadata > > management > > file. > > When accessing out-of-range areas, it simply hits as a hole block > > and > > returns empty data. > >=20 > > Neither memory overrun in user space or kernel space, nor > > out-of-bounds block device access or information leaks will occur. > >=20 > > Well-behaved userland tools read segment information based on the > > statistics obtained via nilfs_get_sustat(), so no problem will > > occur > > (the difference in behavior was visually indistinguishable). > >=20 > > Therefore, I modified the nilfs-utils to perform ill-behaved calls > > and > > tested it. > > Although out-of-range non-existent segments were displayed as empty > > data, no critical issue that compromises kernel stability occurred. > >=20 > > At present, it does not appear to meet the basic criteria for > > stable > > backporting, so when backporting, we need to be able to organize > > and > > demonstrate the reasoning why it is necessary. > >=20 > > Thanks, > > Ryusuke Konishi >=20 > Hi Viacheslav, >=20 > To follow up on my previous email regarding the stable tag: since the > patch includes a Fixes tag, simply dropping 'Cc: stable' will not > prevent automatic pickup by AUTOSEL. >=20 > To strictly prevent automatic backporting while keeping it tracked, > please replace the tag with the following instead of dropping it > entirely: >=20 > Cc: stable+noautosel@kernel.org=C2=A0# Non-fatal bug fix; defer backport > until a real issue is reported >=20 Applied with exchanged CC. Thanks, Slava.