| Message ID | 525D5131.9070007@datus.com |
|---|---|
| State | Changes Requested, archived |
| Delegated to: | David Miller |
| Headers | show |
On Tue, 2013-10-15 at 14:29 +0000, Kelleter, Günther wrote: > Addresses are BCD encoded, not ASCII. x25_addr_ntoa got it right. [] > Wrong length calculation leads to rejection of CALL ACCEPT packets. [] > diff --git a/net/x25/af_x25.c b/net/x25/af_x25.c [] > @@ -98,7 +98,7 @@ int x25_parse_address_block(struct sk_buff *skb, > } > len = *skb->data; > - needed = 1 + (len >> 4) + (len & 0x0f); > + needed = 1 + ((len >> 4) + (len & 0x0f) + 1) / 2; This calculation looks odd. Perhaps use bcd.h instead? -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Am 15.10.2013 19:29, schrieb Joe Perches: > On Tue, 2013-10-15 at 14:29 +0000, Kelleter, Günther wrote: >> Addresses are BCD encoded, not ASCII. x25_addr_ntoa got it right. > [] >> Wrong length calculation leads to rejection of CALL ACCEPT packets. > [] >> diff --git a/net/x25/af_x25.c b/net/x25/af_x25.c > [] >> @@ -98,7 +98,7 @@ int x25_parse_address_block(struct sk_buff *skb, >> } >> len = *skb->data; >> - needed = 1 + (len >> 4) + (len & 0x0f); >> + needed = 1 + ((len >> 4) + (len & 0x0f) + 1) / 2; > This calculation looks odd. > Perhaps use bcd.h instead? > It's just the same calculation as in x25_add_ntoa (last line) and it's used this way by x.25. Two digits are encoded to one byte and the last byte is padded with 0 if the total number of digits is odd.-- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
> On Tue, 2013-10-15 at 14:29 +0000, Kelleter, Günther wrote: > > Addresses are BCD encoded, not ASCII. x25_addr_ntoa got it right. > [] > > Wrong length calculation leads to rejection of CALL ACCEPT packets. > [] > > diff --git a/net/x25/af_x25.c b/net/x25/af_x25.c > [] > > @@ -98,7 +98,7 @@ int x25_parse_address_block(struct sk_buff *skb, > > } > > len = *skb->data; > > - needed = 1 + (len >> 4) + (len & 0x0f); > > + needed = 1 + ((len >> 4) + (len & 0x0f) + 1) / 2; > > This calculation looks odd. Looks correct to me... In X.25 the lengths (in digits) of the called and calling addresses are encoded in the high and low nibbles of one byte and then followed by both addresses with a digit in each nibble. If the length of the first address is odd, the second one isn't byte aligned. David -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Sorry for the previous html mail. This appears to be correct, what length addresses are you getting back in the call accept when this happens? On Wed, Oct 16, 2013 at 7:56 PM, David Laight <David.Laight@aculab.com> wrote: >> On Tue, 2013-10-15 at 14:29 +0000, Kelleter, Günther wrote: >> > Addresses are BCD encoded, not ASCII. x25_addr_ntoa got it right. >> [] >> > Wrong length calculation leads to rejection of CALL ACCEPT packets. >> [] >> > diff --git a/net/x25/af_x25.c b/net/x25/af_x25.c >> [] >> > @@ -98,7 +98,7 @@ int x25_parse_address_block(struct sk_buff *skb, >> > } >> > len = *skb->data; >> > - needed = 1 + (len >> 4) + (len & 0x0f); >> > + needed = 1 + ((len >> 4) + (len & 0x0f) + 1) / 2; >> >> This calculation looks odd. > > Looks correct to me... > In X.25 the lengths (in digits) of the called and calling addresses > are encoded in the high and low nibbles of one byte and then > followed by both addresses with a digit in each nibble. > If the length of the first address is odd, the second one > isn't byte aligned. > > David > > > -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
E.g. called address 7 digits and caller address 3 digits. Called DCE answering without facilities gives us this packet (hex): 37 12 34 56 71 23 00 then x25_parse_address_block() tries to pull 1+7+3 = 11 bytes from the packet (with pskb_may_pull()) which only has 7 bytes. When facilities are included the wrong calculated length has no effect since the facilities make this packet long enough to make pskb_may_pull with wrong number of bytes succeed. later x25_addr_ntoa() correctly pulls 6 bytes for addresses from the packet. Am 17.10.2013 13:02, schrieb Andrew Hendry: > Sorry for the previous html mail. > This appears to be correct, what length addresses are you getting back > in the call accept when this happens? > > On Wed, Oct 16, 2013 at 7:56 PM, David Laight <David.Laight@aculab.com> wrote: >>> On Tue, 2013-10-15 at 14:29 +0000, Kelleter, Günther wrote: >>>> Addresses are BCD encoded, not ASCII. x25_addr_ntoa got it right. >>> [] >>>> Wrong length calculation leads to rejection of CALL ACCEPT packets. >>> [] >>>> diff --git a/net/x25/af_x25.c b/net/x25/af_x25.c >>> [] >>>> @@ -98,7 +98,7 @@ int x25_parse_address_block(struct sk_buff *skb, >>>> } >>>> len = *skb->data; >>>> - needed = 1 + (len >> 4) + (len & 0x0f); >>>> + needed = 1 + ((len >> 4) + (len & 0x0f) + 1) / 2; >>> This calculation looks odd. >> Looks correct to me... >> In X.25 the lengths (in digits) of the called and calling addresses >> are encoded in the high and low nibbles of one byte and then >> followed by both addresses with a digit in each nibble. >> If the length of the first address is odd, the second one >> isn't byte aligned. >> >> David >> >> >>
From: Kelleter, Günther <GKelleter@datus.com> Date: Tue, 15 Oct 2013 14:29:06 +0000 > Addresses are BCD encoded, not ASCII. x25_addr_ntoa got it right. > > Signed-off-by: Guenther Kelleter <gkelleter@datus.com> > --- > Wrong length calculation leads to rejection of CALL ACCEPT packets. This patch doesn't apply because it was severely corrupted by your email client, turn off all encodings etc. in your client, send a test patch to yourself, and do not submit this patch again until you can successfully apply the patch you receive in those test emails. Thanks. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/net/x25/af_x25.c b/net/x25/af_x25.c index 45a3ab5..2daf224 100644 --- a/net/x25/af_x25.c +++ b/net/x25/af_x25.c @@ -98,7 +98,7 @@ int x25_parse_address_block(struct sk_buff *skb, } len = *skb->data; - needed = 1 + (len >> 4) + (len & 0x0f); + needed = 1 + ((len >> 4) + (len & 0x0f) + 1) / 2; if (!pskb_may_pull(skb, needed)) { /* packet is too short to hold the addresses it claims -- 1.8.3.4.71.g0878476 -- To unsubscribe from this list: send the line "unsubscribe netdev" in
Addresses are BCD encoded, not ASCII. x25_addr_ntoa got it right. Signed-off-by: Guenther Kelleter <gkelleter@datus.com> --- Wrong length calculation leads to rejection of CALL ACCEPT packets. net/x25/af_x25.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html