From: Grant Grundler If "location" is > "addr_len" bits, the high bits of location would interfere with the READ_CMD sent to the eeprom controller. A patch was submitted to bug: http://bugzilla.kernel.org/show_bug.cgi?id=4420 which simply truncated the "location", read whatever was in "location modulo addr_len", and returned that value. That avoids confusing the eeprom but seems like the wrong solution to me. Correct would be to not read beyond "1 << addr_len" address of the eeprom. I am submitting two changes to implement this: 1) tulip_read_eeprom will return zero (since we can't return -EINVAL) if this is attempted (defensive programming). 2) In tulip_core.c, fix the tulip_read_eeprom caller so they don't iterate past addr_len bits and make sure the entire tp->eeprom[] array is cleared. I know we don't strictly need both. I would prefer both in the tree since it documents the issue and provides a second "defense" from the bug from creeping back in. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Grant Grundler Cc: Jeff Garzik Signed-off-by: Andrew Morton --- drivers/net/tulip/eeprom.c | 6 ++++++ drivers/net/tulip/tulip_core.c | 7 ++++++- 2 files changed, 12 insertions(+), 1 deletion(-) diff -puN drivers/net/tulip/eeprom.c~tulip-tulip_read_eeprom-fixes-for-bug-4420 drivers/net/tulip/eeprom.c --- a/drivers/net/tulip/eeprom.c~tulip-tulip_read_eeprom-fixes-for-bug-4420 +++ a/drivers/net/tulip/eeprom.c @@ -343,6 +343,12 @@ int __devinit tulip_read_eeprom(struct n void __iomem *ee_addr = tp->base_addr + CSR9; int read_cmd = location | (EE_READ_CMD << addr_len); + /* If location is past the end of what we can address, don't + * read some other location (ie truncate). Just return zero. + */ + if (location > (1 << addr_len) - 1) + return 0; + iowrite32(EE_ENB & ~EE_CS, ee_addr); iowrite32(EE_ENB, ee_addr); diff -puN drivers/net/tulip/tulip_core.c~tulip-tulip_read_eeprom-fixes-for-bug-4420 drivers/net/tulip/tulip_core.c --- a/drivers/net/tulip/tulip_core.c~tulip-tulip_read_eeprom-fixes-for-bug-4420 +++ a/drivers/net/tulip/tulip_core.c @@ -1437,6 +1437,7 @@ static int __devinit tulip_init_one (str EEPROM. */ ee_data = tp->eeprom; + memset(ee_data, 0, sizeof(tp->eeprom)); sum = 0; if (chip_idx == LC82C168) { for (i = 0; i < 3; i++) { @@ -1458,8 +1459,12 @@ static int __devinit tulip_init_one (str /* A serial EEPROM interface, we read now and sort it out later. */ int sa_offset = 0; int ee_addr_size = tulip_read_eeprom(dev, 0xff, 8) & 0x40000 ? 8 : 6; + int ee_max_addr = ((1 << ee_addr_size) - 1) * sizeof(u16); - for (i = 0; i < sizeof(tp->eeprom); i+=2) { + if (ee_max_addr > sizeof(tp->eeprom)) + ee_max_addr = sizeof(tp->eeprom); + + for (i = 0; i < ee_max_addr ; i += sizeof(u16)) { u16 data = tulip_read_eeprom(dev, i/2, ee_addr_size); ee_data[i] = data & 0xff; ee_data[i + 1] = data >> 8; _