[PATCH net v3] e100: prevent shift-out-of-bounds in EEPROM access
From: <hidden>
Date: 2026-08-16 11:39:29
Also in:
intel-wired-lan, lkml
Subsystem:
intel ethernet drivers, networking drivers, the rest · Maintainers:
Tony Nguyen, Przemek Kitszel, Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
From: Yalagada Pavan Kumar <redacted> 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=e0abb1d45ac291ebebeb Signed-off-by: Yalagada Pavan Kumar <redacted> --- 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@gmail.com/ (local) - 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@gmail.com/ (local) --- 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 = i - 16; - if (len > *addr_len) + if (len > *addr_len) { *addr_len = 0; - else - *addr_len -= len; + break; + } + + *addr_len -= len; i = 17; }
@@ -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); - if (!addr_len || addr_len >= 16) { + if (!addr_len || addr_len > 8) { netif_err(nic, probe, nic->netdev, "Invalid EEPROM address length %u\n", addr_len); return -EIO; } - nic->eeprom_wc = 1 << addr_len; + nic->eeprom_wc = (u16)BIT(addr_len); for (addr = 0; addr < nic->eeprom_wc; addr++) { nic->eeprom[addr] = e100_eeprom_read(nic, &addr_len, addr);
@@ -805,14 +807,14 @@ static int e100_eeprom_save(struct nic *nic, u16 start, u16 count) /* Try reading with an 8-bit addr len to discover actual addr len */ e100_eeprom_read(nic, &addr_len, 0); - if (!addr_len || addr_len >= 16) { + if (!addr_len || addr_len > 8) { netif_err(nic, probe, nic->netdev, "Invalid EEPROM address length %u\n", addr_len); return -EIO; } - nic->eeprom_wc = 1 << addr_len; + nic->eeprom_wc = (u16)BIT(addr_len); if (start + count >= nic->eeprom_wc) return -EINVAL;
--
2.43.0