GHSA-cph5-3pgr-c82g Gnark out-of-memory during deserialization with crafted inputs

• Go github.com/consensys/gnark: < 0.11.1 → fixed in 0.11.1

Thanks @pventuzelo for reporting. From the correspondence: > Hi, > > We (Fuzzinglabs & Lambdaclass) found that during deserialization of certain files representing a `VerifyingKey`, an excessive memory allocation is happening consuming a lot of resources and even triggering a crash with the error `fatal error: runtime: out of memory`. > > Please find the details below: > > ## Vulnerability Details > > - Severity: Critical -> DoS > - Affected Component: Deserialization > > ## Environment > > - Compiler Version: go version go1.22.2 linux/amd64 > - Distro Version: Ubuntu 24.04.1 LTS > > - Additional Environment Details: > - `github.com/consensys/gnark v0.11.0` > - `github.com/consensys/gnark-crypto v0.14.1-0.20240909142611-e6b99e74cec1` > > ## Steps to Reproduce > > You can download the needed files here: https://drive.google.com/drive/folders/1KQ5I3vv4bUllvqbatGappwbAkIcR2NI_?usp=sharing > > You have to run > > ```shell > go run gnark_poc.go > ``` > > in a terminal. > > Running the provided code will result in a memory crash or an extremely large memory allocation, which can be observed using the following command: > > ```shell > go tool pprof -web mem.pprof > ``` > > ## Root Cause Analysis > > The provided code loads a `VerifyingKey` from `old.vk` by calling the `ReadFrom` function. This function is implemented in backend/groth16/bn254/marshal.go within the gnark library. > > The provided example uses the elliptic curve BN-254, so the code resides in the backend/groth16/bn254/ repertory. However, the same error exists in other repertories, such as backend/groth16/bls12-377/. > > At line 207, a slice is allocated with a length of `nbCommitments`. This variable is directly extracted from the deserialized file, which, in our case, has a value of `2,327,186,600`. This large value may be too big for some configurations, leading to memory allocations of approximately ±1 TB, as observed with `pprof`. > > ## Detailed Behavior > > ```shell > go run gnark_poc.go > ``` > > ``` > fatal error: runtime: out of memory > > runtime stack: > runtime.throw({0x5fe946?, 0x2052ae?}) > /usr/lib/go-1.22/src/runtime/panic.go:1023 +0x5c fp=0x7ffd65b321a0 sp=0x7ffd65b32170 pc=0x438a9c > runtime.sysMapOS(0xc000400000, 0x8ab6400000) > /usr/lib/go-1.22/src/runtime/mem_linux.go:167 +0x11b fp=0x7ffd65b321e0 sp=0x7ffd65b321a0 pc=0x418bbb > runtime.sysMap(0xc000400000, 0x8ab6400000, 0x7b19c8?) > /usr/lib/go-1.22/src/runtime/mem.go:155 +0x34 fp=0x7ffd65b32200 sp=0x7ffd65b321e0 pc=0x418634 > runtime.(*mheap).grow(0x7a17c0, 0x455b066?) > /usr/lib/go-1.22/src/runtime/mheap.go:1534 +0x236 fp=0x7ffd65b32270 sp=0x7ffd65b32200 pc=0x42b176 > runtime.(*mheap).allocSpan(0x7a17c0, 0x455b066, 0x0, 0x1) > /usr/lib/go-1.22/src/runtime/mheap.go:1246 +0x1b0 fp=0x7ffd65b32310 sp=0x7ffd65b32270 pc=0x42a850 > runtime.(*mheap).alloc.func1() > /usr/lib/go-1.22/src/runtime/mheap.go:964 +0x5c fp=0x7ffd65b32358 sp=0x7ffd65b32310 pc=0x42a2fc > runtime.systemstack(0x46d79f) > /usr/lib/go-1.22/src/runtime/asm_amd64.s:509 +0x4a fp=0x7ffd65b32368 sp=0x7ffd65b32358 pc=0x46912a > > goroutine 1 gp=0xc0000061c0 m=0 mp=0x798ca0 [running]: > runtime.systemstack_switch() > /usr/lib/go-1.22/src/runtime/asm_amd64.s:474 +0x8 fp=0xc000031b68 sp=0xc000031b58 pc=0x4690c8 > runtime.(*mheap).alloc(0x5bc040?, 0xc00012bb08?, 0xa0?) > /usr/lib/go-1.22/src/runtime/mheap.go:958 +0x5b fp=0xc000031bb0 sp=0xc000031b68 pc=0x42a25b > runtime.(*mcache).allocLarge(0xc000126510?, 0x8ab60ca800, 0x1) > /usr/lib/go-1.22/src/runtime/mcache.go:234 +0x87 fp=0xc000031c00 sp=0xc000031bb0 pc=0x4176e7 > runtime.mallocgc(0x8ab60ca800, 0x5d92a0, 0x1) > /usr/lib/go-1.22/src/runtime/malloc.go:1165 +0x597 fp=0xc000031c88 sp=0xc000031c00 pc=0x40ef97 > runtime.makeslice(0xc00011c180?, 0x0?, 0x2?) > /usr/lib/go-1.22/src/runtime/slice.go:107 +0x49 fp=0xc000031cb0 sp=0xc000031c88 pc=0x4500c9 > github.com/consensys/gnark/backend/groth16/bn254.(*VerifyingKey).readFrom(0xc0001b7088.readFrom(0xc0001b7088), {0x6598a0, 0xc00011dc50}, 0x0) > /home/raunan/go/pkg/mod/github.com/!ronan!thoraval/[email protected]/backend/groth16/bn254/marshal.go:214 +0x765 fp=0xc000031ea8 sp=0xc000031cb0 pc=0x59b205 > github.com/consensys/gnark/backend/groth16/bn254.(*VerifyingKey).ReadFrom(0x100469020.ReadFrom(0x100469020)?, {0x6598a0?, 0xc00011dc50?}) > /home/raunan/go/pkg/mod/github.com/!ronan!thoraval/[email protected]/backend/groth16/bn254/marshal.go:166 +0x1f fp=0xc000031ed8 sp=0xc000031ea8 pc=0x59aa5f > main.main() > /home/raunan/gnark_poc/gnark_poc/gnark_poc.go:19 +0xba fp=0xc000031f50 sp=0xc000031ed8 pc=0x5addda > runtime.main() > /usr/lib/go-1.22/src/runtime/proc.go:271 +0x29d fp=0xc000031fe0 sp=0xc000031f50 pc=0x43b55d > runtime.goexit({}) > /usr/lib/go-1.22/src/runtime/asm_amd64.s:1695 +0x1 fp=0xc000031fe8 sp=0xc000031fe0 pc=0x46b0e1 > > goroutine 2 gp=0xc000006c40 m=nil [force gc (idle)]: > runtime.gopark(0x0?, 0x0?, 0x0?, 0x0?, 0x0?) > /usr/lib/go-1.22/src/runtime/proc.go:402 +0xce fp=0xc000074fa8 sp=0xc000074f88 pc=0x43b98e > runtime.goparkunlock(...) > /usr/lib/go-1.22/src/runtime/proc.go:408 > runtime.forcegchelper() > /usr/lib/go-1.22/src/runtime/proc.go:326 +0xb3 fp=0xc000074fe0 sp=0xc000074fa8 pc=0x43b813 > runtime.goexit({}) > /usr/lib/go-1.22/src/runtime/asm_amd64.s:1695 +0x1 fp=0xc000074fe8 sp=0xc000074fe0 pc=0x46b0e1 > created by runtime.init.6 in goroutine 1 > /usr/lib/go-1.22/src/runtime/proc.go:314 +0x1a > > goroutine 3 gp=0xc000007180 m=nil [GC sweep wait]: > runtime.gopark(0x0?, 0x0?, 0x0?, 0x0?, 0x0?) > /usr/lib/go-1.22/src/runtime/proc.go:402 +0xce fp=0xc000075780 sp=0xc000075760 pc=0x43b98e > runtime.goparkunlock(...) > /usr/lib/go-1.22/src/runtime/proc.go:408 > runtime.bgsweep(0xc0000240e0) > /usr/lib/go-1.22/src/runtime/mgcsweep.go:278 +0x94 fp=0xc0000757c8 sp=0xc000075780 pc=0x426cf4 > runtime.gcenable.gowrap1() > /usr/lib/go-1.22/src/runtime/mgc.go:203 +0x25 fp=0xc0000757e0 sp=0xc0000757c8 pc=0x41b845 > runtime.goexit({}) > /usr/lib/go-1.22/src/runtime/asm_amd64.s:1695 +0x1 fp=0xc0000757e8 sp=0xc0000757e0 pc=0x46b0e1 > created by runtime.gcenable in goroutine 1 > /usr/lib/go-1.22/src/runtime/mgc.go:203 +0x66 > > goroutine 4 gp=0xc000007340 m=nil [GC scavenge wait]: > runtime.gopark(0xc0000240e0?, 0x657100?, 0x1?, 0x0?, 0xc000007340?) > /usr/lib/go-1.22/src/runtime/proc.go:402 +0xce fp=0xc000075f78 sp=0xc000075f58 pc=0x43b98e > runtime.goparkunlock(...) > /usr/lib/go-1.22/src/runtime/proc.go:408 > runtime.(*scavengerState).park(0x797520) > /usr/lib/go-1.22/src/runtime/mgcscavenge.go:425 +0x49 fp=0xc000075fa8 sp=0xc000075f78 pc=0x4246e9 > runtime.bgscavenge(0xc0000240e0) > /usr/lib/go-1.22/src/runtime/mgcscavenge.go:653 +0x3c fp=0xc000075fc8 sp=0xc000075fa8 pc=0x424c7c > runtime.gcenable.gowrap2() > /usr/lib/go-1.22/src/runtime/mgc.go:204 +0x25 fp=0xc000075fe0 sp=0xc000075fc8 pc=0x41b7e5 > runtime.goexit({}) > /usr/lib/go-1.22/src/runtime/asm_amd64.s:1695 +0x1 fp=0xc000075fe8 sp=0xc000075fe0 pc=0x46b0e1 > c…