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Fix out-of-bounds slicing in std/varints (#23868)

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Corrects a slicing mistake in the `std/varints` implementation which
caused it to fail when writing large numbers into buffers smaller than
10..13-bytes, now 9-byte buffers are sufficient as the documentation
states.
This commit is contained in:
Buldram
2024-07-22 01:11:14 -04:00
committed by GitHub
parent 1c287fb960
commit 2d2a7f2347
2 changed files with 7 additions and 7 deletions
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12
lib/std/varints.nim
View File

@@ -82,29 +82,29 @@ proc writeVu64*(z: var openArray[byte], x: uint64): int =
z[3] = cast[uint8](y)
return 4
z[0] = 251
varintWrite32(toOpenArray(z, 1, z.high-1), y)
varintWrite32(toOpenArray(z, 1, 4), y)
return 5
if w <= 255:
z[0] = 252
z[1] = cast[uint8](w)
varintWrite32(toOpenArray(z, 2, z.high-2), y)
varintWrite32(toOpenArray(z, 2, 5), y)
return 6
if w <= 65535:
z[0] = 253
z[1] = cast[uint8](w shr 8)
z[2] = cast[uint8](w)
varintWrite32(toOpenArray(z, 3, z.high-3), y)
varintWrite32(toOpenArray(z, 3, 6), y)
return 7
if w <= 16777215:
z[0] = 254
z[1] = cast[uint8](w shr 16)
z[2] = cast[uint8](w shr 8)
z[3] = cast[uint8](w)
varintWrite32(toOpenArray(z, 4, z.high-4), y)
varintWrite32(toOpenArray(z, 4, 7), y)
return 8
z[0] = 255
varintWrite32(toOpenArray(z, 1, z.high-1), w)
varintWrite32(toOpenArray(z, 5, z.high-5), y)
varintWrite32(toOpenArray(z, 1, 4), w)
varintWrite32(toOpenArray(z, 5, 8), y)
return 9
proc sar(a, b: int64): int64 =

2
tests/stdlib/tvarints.nim
View File

@@ -33,7 +33,7 @@ block:
doAssert cast[float64](got) == test
block:
var hugeIntArray: array[50, byte]
var hugeIntArray: array[9, byte]
var readedInt: uint64
template chk(a) =