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([2405:201:c052:b00b:c8db:7e2d:fa79:eaee]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-320d61e1cccsm22520860eec.8.2026.08.16.04.39.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 16 Aug 2026 04:39:25 -0700 (PDT) From: pavankumaryalagada@gmail.com To: anthony.l.nguyen@intel.com, przemyslaw.kitszel@intel.com Cc: andrew+netdev@lunn.ch, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, intel-wired-lan@lists.osuosl.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, skhan@linuxfoundation.org, syzbot+e0abb1d45ac291ebebeb@syzkaller.appspotmail.com, kohei@enjuk.jp, aleksandr.loktionov@intel.com, Yalagada Pavan Kumar Subject: [PATCH net v3] e100: prevent shift-out-of-bounds in EEPROM access Date: Sun, 16 Aug 2026 17:07:54 +0530 Message-ID: <20260816113754.22900-1-pavankumaryalagada@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Yalagada Pavan Kumar When reading the EEPROM address length, e100_eeprom_read() can return an invalid length. This value is then used as a shift count when calculating eeprom_wc, resulting in a shift-out-of-bounds UBSAN warning. Stop EEPROM address probing if the detected address length exceeds the initial address length to prevent addr_len from underflowing. Validate addr_len after reading it from the EEPROM in both e100_eeprom_load() and e100_eeprom_save(), and return -EIO if the value is zero or greater than 8. Reported-by: syzbot+e0abb1d45ac291ebebeb@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=3De0abb1d45ac291ebebeb Signed-off-by: Yalagada Pavan Kumar --- v3: - Prevent addr_len underflow during EEPROM probing. - Use BIT() and explicitly cast the result to u16 when assigning eeprom_wc. - Update the commit message and subject to reflect the scope of the fix. - verify the UBSAN failure with syzkaller reproducer before the fix and its absence after the fix. v2: https://lore.kernel.org/all/20260810083355.21631-1-pavankumaryalagada@g= mail.com/ - Return -EIO instead of -EINVAL for an invalid EEPROM address length. - Validate addr_len in e100_eeprom_save() as well. - Drop the unnecessary 1U change in the shift. - Update the commit message. v1: https://lore.kernel.org/all/20260807145626.52692-1-pavankumaryalagada@g= mail.com/ --- drivers/net/ethernet/intel/e100.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-) diff --git a/drivers/net/ethernet/intel/e100.c b/drivers/net/ethernet/intel= /e100.c index 464dc2d6cdb5..5165f1d3c98f 100644 --- a/drivers/net/ethernet/intel/e100.c +++ b/drivers/net/ethernet/intel/e100.c @@ -746,10 +746,12 @@ static __le16 e100_eeprom_read(struct nic *nic, u16 *= addr_len, u16 addr) if (!(ctrl & eedo) && i > 16) { u16 len =3D i - 16; =20 - if (len > *addr_len) + if (len > *addr_len) { *addr_len =3D 0; - else - *addr_len -=3D len; + break; + } + + *addr_len -=3D len; i =3D 17; } =20 @@ -771,14 +773,14 @@ static int e100_eeprom_load(struct nic *nic) /* Try reading with an 8-bit addr len to discover actual addr len */ e100_eeprom_read(nic, &addr_len, 0); =20 - if (!addr_len || addr_len >=3D 16) { + if (!addr_len || addr_len > 8) { netif_err(nic, probe, nic->netdev, "Invalid EEPROM address length %u\n", addr_len); return -EIO; } =20 - nic->eeprom_wc =3D 1 << addr_len; + nic->eeprom_wc =3D (u16)BIT(addr_len); =20 for (addr =3D 0; addr < nic->eeprom_wc; addr++) { nic->eeprom[addr] =3D e100_eeprom_read(nic, &addr_len, addr); @@ -805,14 +807,14 @@ static int e100_eeprom_save(struct nic *nic, u16 star= t, u16 count) /* Try reading with an 8-bit addr len to discover actual addr len */ e100_eeprom_read(nic, &addr_len, 0); =20 - if (!addr_len || addr_len >=3D 16) { + if (!addr_len || addr_len > 8) { netif_err(nic, probe, nic->netdev, "Invalid EEPROM address length %u\n", addr_len); return -EIO; } =20 - nic->eeprom_wc =3D 1 << addr_len; + nic->eeprom_wc =3D (u16)BIT(addr_len); =20 if (start + count >=3D nic->eeprom_wc) return -EINVAL; --=20 2.43.0