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tg3: fix length overflow in VPD firmware parsing

commit 715230a upstream.

Commit 184b890 ("tg3: Use VPD fw version
when present") introduced VPD parsing that contained a potential length
overflow.

Limit the hardware's reported firmware string length (max 255 bytes) to
stay inside the driver's firmware string length (32 bytes). On overflow,
truncate the formatted firmware string instead of potentially overwriting
portions of the tg3 struct.

http://cansecwest.com/slides/2013/PrivateCore%20CSW%202013.pdf

Signed-off-by: Kees Cook <keescook@chromium.org>
Reported-by: Oded Horovitz <oded@privatecore.com>
Reported-by: Brad Spengler <spender@grsecurity.net>
Cc: Matt Carlson <mcarlson@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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1 parent 554293b commit 60f18f483ee41bfc61d31b9da18f91fd19ab872b @kees kees committed with gregkh Mar 27, 2013
Showing with 5 additions and 2 deletions.
  1. +5 −2 drivers/net/ethernet/broadcom/tg3.c
@@ -13590,8 +13590,11 @@ static void __devinit tg3_read_vpd(struct tg3 *tp)
if (j + len > block_end)
goto partno;
- memcpy(tp->fw_ver, &vpd_data[j], len);
- strncat(tp->fw_ver, " bc ", vpdlen - len - 1);
+ if (len >= sizeof(tp->fw_ver))
+ len = sizeof(tp->fw_ver) - 1;
+ memset(tp->fw_ver, 0, sizeof(tp->fw_ver));
+ snprintf(tp->fw_ver, sizeof(tp->fw_ver), "%.*s bc ", len,
+ &vpd_data[j]);
}
partno:

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