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arm: CVE-2020-6096: fix memcpy and memmove for negative length [BZ #25620]

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Unsigned branch instructions could be used for r2 to fix the wrong
behavior when a negative length is passed to memcpy and memmove.
This commit fixes the generic arm implementation of memcpy amd memmove.
This commit is contained in:
Evgeny Eremin 2020-07-08 14:18:19 +02:00 committed by Florian Weimer
parent 78e02c4698
commit 79a4fa341b
2 changed files with 20 additions and 28 deletions
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24
sysdeps/arm/memcpy.S
View File

@ -68,7 +68,7 @@ ENTRY(memcpy)
cfi_remember_state
subs r2, r2, #4
blt 8f
blo 8f
ands ip, r0, #3
PLD( pld [r1, #0] )
bne 9f
@ -82,7 +82,7 @@ ENTRY(memcpy)
cfi_rel_offset (r6, 4)
cfi_rel_offset (r7, 8)
cfi_rel_offset (r8, 12)
blt 5f
blo 5f
CALGN( ands ip, r1, #31 )
CALGN( rsb r3, ip, #32 )
@ -98,9 +98,9 @@ ENTRY(memcpy)
#endif
PLD( pld [r1, #0] )
2: PLD( subs r2, r2, #96 )
2: PLD( cmp r2, #96 )
PLD( pld [r1, #28] )
PLD( blt 4f )
PLD( blo 4f )
PLD( pld [r1, #60] )
PLD( pld [r1, #92] )
@ -108,9 +108,7 @@ ENTRY(memcpy)
4: ldmia r1!, {r3, r4, r5, r6, r7, r8, ip, lr}
subs r2, r2, #32
stmia r0!, {r3, r4, r5, r6, r7, r8, ip, lr}
bge 3b
PLD( cmn r2, #96 )
PLD( bge 4b )
bhs 3b
5: ands ip, r2, #28
rsb ip, ip, #32
@ -222,7 +220,7 @@ ENTRY(memcpy)
strbge r4, [r0], #1
subs r2, r2, ip
strb lr, [r0], #1
blt 8b
blo 8b
ands ip, r1, #3
beq 1b
@ -236,7 +234,7 @@ ENTRY(memcpy)
.macro forward_copy_shift pull push
subs r2, r2, #28
blt 14f
blo 14f
CALGN( ands ip, r1, #31 )
CALGN( rsb ip, ip, #32 )
@ -253,9 +251,9 @@ ENTRY(memcpy)
cfi_rel_offset (r10, 16)
PLD( pld [r1, #0] )
PLD( subs r2, r2, #96 )
PLD( cmp r2, #96 )
PLD( pld [r1, #28] )
PLD( blt 13f )
PLD( blo 13f )
PLD( pld [r1, #60] )
PLD( pld [r1, #92] )
@ -280,9 +278,7 @@ ENTRY(memcpy)
mov ip, ip, PULL #\pull
orr ip, ip, lr, PUSH #\push
stmia r0!, {r3, r4, r5, r6, r7, r8, r10, ip}
bge 12b
PLD( cmn r2, #96 )
PLD( bge 13b )
bhs 12b
pop {r5 - r8, r10}
cfi_adjust_cfa_offset (-20)

24
sysdeps/arm/memmove.S
View File

@ -85,7 +85,7 @@ ENTRY(memmove)
add r1, r1, r2
add r0, r0, r2
subs r2, r2, #4
blt 8f
blo 8f
ands ip, r0, #3
PLD( pld [r1, #-4] )
bne 9f
@ -99,7 +99,7 @@ ENTRY(memmove)
cfi_rel_offset (r6, 4)
cfi_rel_offset (r7, 8)
cfi_rel_offset (r8, 12)
blt 5f
blo 5f
CALGN( ands ip, r1, #31 )
CALGN( sbcsne r4, ip, r2 ) @ C is always set here
@ -114,9 +114,9 @@ ENTRY(memmove)
#endif
PLD( pld [r1, #-4] )
2: PLD( subs r2, r2, #96 )
2: PLD( cmp r2, #96 )
PLD( pld [r1, #-32] )
PLD( blt 4f )
PLD( blo 4f )
PLD( pld [r1, #-64] )
PLD( pld [r1, #-96] )
@ -124,9 +124,7 @@ ENTRY(memmove)
4: ldmdb r1!, {r3, r4, r5, r6, r7, r8, ip, lr}
subs r2, r2, #32
stmdb r0!, {r3, r4, r5, r6, r7, r8, ip, lr}
bge 3b
PLD( cmn r2, #96 )
PLD( bge 4b )
bhs 3b
5: ands ip, r2, #28
rsb ip, ip, #32
@ -237,7 +235,7 @@ ENTRY(memmove)
strbge r4, [r0, #-1]!
subs r2, r2, ip
strb lr, [r0, #-1]!
blt 8b
blo 8b
ands ip, r1, #3
beq 1b
@ -251,7 +249,7 @@ ENTRY(memmove)
.macro backward_copy_shift push pull
subs r2, r2, #28
blt 14f
blo 14f
CALGN( ands ip, r1, #31 )
CALGN( rsb ip, ip, #32 )
@ -268,9 +266,9 @@ ENTRY(memmove)
cfi_rel_offset (r10, 16)
PLD( pld [r1, #-4] )
PLD( subs r2, r2, #96 )
PLD( cmp r2, #96 )
PLD( pld [r1, #-32] )
PLD( blt 13f )
PLD( blo 13f )
PLD( pld [r1, #-64] )
PLD( pld [r1, #-96] )
@ -295,9 +293,7 @@ ENTRY(memmove)
mov r4, r4, PUSH #\push
orr r4, r4, r3, PULL #\pull
stmdb r0!, {r4 - r8, r10, ip, lr}
bge 12b
PLD( cmn r2, #96 )
PLD( bge 13b )
bhs 12b
pop {r5 - r8, r10}
cfi_adjust_cfa_offset (-20)