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Sat, 08 Aug 2026 12:10:22 -0700 (PDT) Date: Sun, 9 Aug 2026 00:39:21 +0530 From: Yalagada Pavan Kumar To: Kohei Enju Cc: intel-wired-lan@lists.osuosl.org, netdev@vger.kernel.org, anthony.l.nguyen@intel.com, przemyslaw.kitszel@intel.com, andrew+netdev@lunn.ch, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, linux-kernel@vger.kernel.org, skhan@linuxfoundation.org, syzbot+e0abb1d45ac291ebebeb@syzkaller.appspotmail.com Subject: Re: [Intel-wired-lan] [PATCH] e100: prevent shift out-of-bounds in e100_eeprom_load Message-ID: References: <20260807145626.52692-1-pavankumaryalagada@gmail.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Sun, Aug 09, 2026 at 12:12:31AM +0900, Kohei Enju wrote: > On 08/07 20:26, pavankumaryalagada@gmail.com wrote: > > From: Yalagada Pavan Kumar > > > > When reading the EEPROM address length, e100_eeprom_read() can return > > an invalid length (0 or >= 16). Passing an invalid addr_len to bit-shift > > operations causes a shift out-of-bounds, triggering a kernel panic or > > UBSAN warning. > > > > Validate addr_len after reading it from EEPROM and return -EINVAL if > > the value is out of bounds. Additionally, use 1U to prevent > > signed integer overflow when calculating eeprom_wc. > > > > Reported-by: syzbot+e0abb1d45ac291ebebeb@syzkaller.appspotmail.com > > Tested-by: syzbot+e0abb1d45ac291ebebeb@syzkaller.appspotmail.com > > Closes: https://syzkaller.appspot.com/bug?extid=e0abb1d45ac291ebebeb > > Signed-off-by: Yalagada Pavan Kumar > > --- > > Tested using syzbot c reproducer. > > --- > > drivers/net/ethernet/intel/e100.c | 17 +++++++++++++++-- > > 1 file changed, 15 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/net/ethernet/intel/e100.c b/drivers/net/ethernet/intel/e100.c > > index 29960762e64a..1de5cd41ea0c 100644 > > --- a/drivers/net/ethernet/intel/e100.c > > +++ b/drivers/net/ethernet/intel/e100.c > > @@ -744,7 +744,12 @@ static __le16 e100_eeprom_read(struct nic *nic, u16 *addr_len, u16 addr) > > * complete address. Use this to adjust addr_len. */ > > ctrl = ioread8(&nic->csr->eeprom_ctrl_lo); > > if (!(ctrl & eedo) && i > 16) { > > - *addr_len -= (i - 16); > > + u16 len = i - 16; > > + > > + if (len > *addr_len) > > + *addr_len = 0; > > + else > > + *addr_len -= len; > > i = 17; > > } > > > > @@ -765,7 +770,15 @@ 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); > > - nic->eeprom_wc = 1 << addr_len; > > + > > + if (!addr_len || addr_len >= 16) { > > + netif_err(nic, probe, nic->netdev, > > + "Invalid EEPROM address length %u\n", > > + addr_len); > > + return -EINVAL; > > An invalid address length here appears to indicate an unexpected > response from the EEPROM, rather than an invalid argument. Therefore, > -EINVAL seems somewhat misleading. Would -EIO be more appropriate here? Agreed, addr_len comes from an unexpected EEPROM response, so i will change -EINVAL to -EIO. > > Also, e100_eeprom_save() seems to have the same pattern. Shouldn't we > fix that as well? yes, i'll fix e100_eeprom_save() as well. > > > + } > > + > > + nic->eeprom_wc = 1U << addr_len; > > The commit message says that the U suffix prevents signed integer > overflow. However, after the validation addr_len is in [1, 15], so 1 << > addr_len cannot overflow an int. I think what prevents the out-of-bounds > shift is the validation, not the U. Agreed, I'll remove the unnecessary U suffix. I made these changes and will send v2. > > > > > for (addr = 0; addr < nic->eeprom_wc; addr++) { > > nic->eeprom[addr] = e100_eeprom_read(nic, &addr_len, addr); > > -- > > 2.43.0 > >