--- /dev/null
+Upstream-Status: Backport
+ https://git.lysator.liu.se/nettle/nettle/commit/fa269b6ad06dd13c901dbd84a12e52b918a09cd7
+
+CVE: CVE-2015-8804
+Signed-off-by: Armin Kuster <akuster@mvista.com>
+
+Index: nettle-2.7.1/ChangeLog
+===================================================================
+--- nettle-2.7.1.orig/ChangeLog
++++ nettle-2.7.1/ChangeLog
+@@ -1,3 +1,11 @@
++2015-12-15 Niels Möller <nisse@lysator.liu.se>
++
++ * x86_64/ecc-384-modp.asm: Fixed carry propagation bug. Problem
++ reported by Hanno Böck. Simplified the folding to always use
++ non-negative carry, the old code attempted to add in a carry which
++ could be either positive or negative, but didn't get that case
++ right.
++
+ 2015-12-10 Niels Möller <nisse@lysator.liu.se>
+
+ * ecc-256.c (ecc_256_modp): Fixed carry propagation bug. Problem
+Index: nettle-2.7.1/x86_64/ecc-384-modp.asm
+===================================================================
+--- nettle-2.7.1.orig/x86_64/ecc-384-modp.asm
++++ nettle-2.7.1/x86_64/ecc-384-modp.asm
+@@ -20,7 +20,7 @@ C MA 02111-1301, USA.
+ .file "ecc-384-modp.asm"
+
+ define(<RP>, <%rsi>)
+-define(<D4>, <%rax>)
++define(<D5>, <%rax>)
+ define(<T0>, <%rbx>)
+ define(<T1>, <%rcx>)
+ define(<T2>, <%rdx>)
+@@ -35,8 +35,8 @@ define(<H4>, <%r13>)
+ define(<H5>, <%r14>)
+ define(<C2>, <%r15>)
+ define(<C0>, H5) C Overlap
+-define(<D0>, RP) C Overlap
+-define(<TMP>, H4) C Overlap
++define(<TMP>, RP) C Overlap
++
+
+ PROLOGUE(nettle_ecc_384_modp)
+ W64_ENTRY(2, 0)
+@@ -48,34 +48,38 @@ PROLOGUE(nettle_ecc_384_modp)
+ push %r14
+ push %r15
+
+- C First get top 2 limbs, which need folding twice
++ C First get top 2 limbs, which need folding twice.
++ C B^10 = B^6 + B^4 + 2^32 (B-1)B^4.
++ C We handle the terms as follow:
+ C
+- C H5 H4
+- C -H5
+- C ------
+- C H0 D4
++ C B^6: Folded immediatly.
+ C
+- C Then shift right, (H1,H0,D4) <-- (H0,D4) << 32
+- C and add
++ C B^4: Delayed, added in in the next folding.
+ C
+- C H5 H4
+- C H1 H0
+- C ----------
+- C C2 H1 H0
+-
+- mov 80(RP), D4
+- mov 88(RP), H0
+- mov D4, H4
+- mov H0, H5
+- sub H0, D4
+- sbb $0, H0
+-
+- mov D4, T2
+- mov H0, H1
+- shl $32, H0
+- shr $32, T2
++ C 2^32(B-1) B^4: Low half limb delayed until the next
++ C folding. Top 1.5 limbs subtracted and shifter now, resulting
++ C in 2.5 limbs. The low limb saved in D5, high 1.5 limbs added
++ C in.
++
++ mov 80(RP), H4
++ mov 88(RP), H5
++ C Shift right 32 bits, into H1, H0
++ mov H4, H0
++ mov H5, H1
++ mov H5, D5
+ shr $32, H1
+- or T2, H0
++ shl $32, D5
++ shr $32, H0
++ or D5, H0
++
++ C H1 H0
++ C - H1 H0
++ C --------
++ C H1 H0 D5
++ mov H0, D5
++ neg D5
++ sbb H1, H0
++ sbb $0, H1
+
+ xor C2, C2
+ add H4, H0
+@@ -114,118 +118,95 @@ PROLOGUE(nettle_ecc_384_modp)
+ adc H3, T5
+ adc $0, C0
+
+- C H3 H2 H1 H0 0
+- C - H4 H3 H2 H1 H0
+- C ---------------
+- C H3 H2 H1 H0 D0
+-
+- mov XREG(D4), XREG(D4)
+- mov H0, D0
+- neg D0
+- sbb H1, H0
+- sbb H2, H1
+- sbb H3, H2
+- sbb H4, H3
+- sbb $0, D4
+-
+- C Shift right. High bits are sign, to be added to C0.
+- mov D4, TMP
+- sar $32, TMP
+- shl $32, D4
+- add TMP, C0
+-
++ C Shift left, including low half of H4
+ mov H3, TMP
++ shl $32, H4
+ shr $32, TMP
+- shl $32, H3
+- or TMP, D4
++ or TMP, H4
+
+ mov H2, TMP
++ shl $32, H3
+ shr $32, TMP
+- shl $32, H2
+ or TMP, H3
+
+ mov H1, TMP
++ shl $32, H2
+ shr $32, TMP
+- shl $32, H1
+ or TMP, H2
+
+ mov H0, TMP
++ shl $32, H1
+ shr $32, TMP
+- shl $32, H0
+ or TMP, H1
+
+- mov D0, TMP
+- shr $32, TMP
+- shl $32, D0
+- or TMP, H0
++ shl $32, H0
++
++ C H4 H3 H2 H1 H0 0
++ C - H4 H3 H2 H1 H0
++ C ---------------
++ C H4 H3 H2 H1 H0 TMP
+
+- add D0, T0
++ mov H0, TMP
++ neg TMP
++ sbb H1, H0
++ sbb H2, H1
++ sbb H3, H2
++ sbb H4, H3
++ sbb $0, H4
++
++ add TMP, T0
+ adc H0, T1
+ adc H1, T2
+ adc H2, T3
+ adc H3, T4
+- adc D4, T5
++ adc H4, T5
+ adc $0, C0
+
+ C Remains to add in C2 and C0
+- C C0 C0<<32 (-2^32+1)C0
+- C C2 C2<<32 (-2^32+1)C2
+- C where C2 is always positive, while C0 may be -1.
++ C Set H1, H0 = (2^96 - 2^32 + 1) C0
+ mov C0, H0
+ mov C0, H1
+- mov C0, H2
+- sar $63, C0 C Get sign
+ shl $32, H1
+- sub H1, H0 C Gives borrow iff C0 > 0
++ sub H1, H0
+ sbb $0, H1
+- add C0, H2
+
++ C Set H3, H2 = (2^96 - 2^32 + 1) C2
++ mov C2, H2
++ mov C2, H3
++ shl $32, H3
++ sub H3, H2
++ sbb $0, H3
++ add C0, H2 C No carry. Could use lea trick
++
++ xor C0, C0
+ add H0, T0
+ adc H1, T1
+- adc $0, H2
+- adc $0, C0
+-
+- C Set (H1 H0) <-- C2 << 96 - C2 << 32 + 1
+- mov C2, H0
+- mov C2, H1
+- shl $32, H1
+- sub H1, H0
+- sbb $0, H1
+-
+- add H2, H0
+- adc C0, H1
+- adc C2, C0
+- mov C0, H2
+- sar $63, C0
+- add H0, T2
+- adc H1, T3
+- adc H2, T4
+- adc C0, T5
+- sbb C0, C0
++ adc H2, T2
++ adc H3, T3
++ adc C2, T4
++ adc D5, T5 C Value delayed from initial folding
++ adc $0, C0 C Use sbb and switch sign?
+
+ C Final unlikely carry
+ mov C0, H0
+ mov C0, H1
+- mov C0, H2
+- sar $63, C0
+ shl $32, H1
+ sub H1, H0
+ sbb $0, H1
+- add C0, H2
+
+ pop RP
+
+- sub H0, T0
++ add H0, T0
+ mov T0, (RP)
+- sbb H1, T1
++ adc H1, T1
+ mov T1, 8(RP)
+- sbb H2, T2
++ adc C0, T2
+ mov T2, 16(RP)
+- sbb C0, T3
++ adc $0, T3
+ mov T3, 24(RP)
+- sbb C0, T4
++ adc $0, T4
+ mov T4, 32(RP)
+- sbb C0, T5
++ adc $0, T5
+ mov T5, 40(RP)
+
+ pop %r15
