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crypto/tls: segfault when calling tlsrsakex.IncNonDefault() #65991

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michaelbeaumont opened this issue Feb 28, 2024 · 5 comments
Open

crypto/tls: segfault when calling tlsrsakex.IncNonDefault() #65991

michaelbeaumont opened this issue Feb 28, 2024 · 5 comments
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NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one.
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Go1.23

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@michaelbeaumont
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michaelbeaumont commented Feb 28, 2024 •
edited

Go version

go version go1.22.0 linux/amd64

Output of go env in your module/workspace:

GO111MODULE=''
GOARCH='amd64'
GOBIN='/home/mike/.local/bin'
GOCACHE='/home/mike/.cache/go-build'
GOENV='/home/mike/.config/go/env'
GOEXE=''
GOEXPERIMENT='boringcrypto'
GOFLAGS='-trimpath -tags=opa_no_oci'
GOHOSTARCH='amd64'
GOHOSTOS='linux'
GOINSECURE=''
GOMODCACHE='/home/mike/go/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='linux'
GOPATH='/home/mike/go'
GOPRIVATE=''
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/home/mike/go/pkg/mod/golang.org/toolchain@v0.0.1-go1.22.0.linux-amd64'
GOSUMDB='sum.golang.org'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/home/mike/go/pkg/mod/golang.org/toolchain@v0.0.1-go1.22.0.linux-amd64/pkg/tool/linux_amd64'
GOVCS=''
GOVERSION='go1.22.0'
GCCGO='gccgo'
GOAMD64='v1'
AR='ar'
CC='gcc'
CXX='g++'
CGO_ENABLED='0'
GOMOD='/home/mike/projects/project/go.mod'
GOWORK=''
CGO_CFLAGS='-O2 -g'
CGO_CPPFLAGS=''
CGO_CXXFLAGS='-O2 -g'
CGO_FFLAGS='-O2 -g'
CGO_LDFLAGS='-O2 -g'
PKG_CONFIG='pkg-config'
GOGCCFLAGS='-fPIC -m64 -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/tmp/go-build1264452044=/tmp/go-build -gno-record-gcc-switches'

What did you do?

Tried to connect to a postgres DB over TLS using jackc/pgx (see stack trace).

What did you see happen?

A panic when crypto/tls calls internal/godebug.(*Setting).IncNonDefault:

panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x552252]
goroutine 1 [running]:
internal/godebug.(*Setting).IncNonDefault(0x32c3a60?)
	internal/godebug/godebug.go:102 +0x12
crypto/tls.(*clientHandshakeState).pickCipherSuite(0xc00103f450)
	crypto/tls/handshake_client.go:530 +0xbd
crypto/tls.(*clientHandshakeState).processServerHello(0xc00103f450)
	crypto/tls/handshake_client.go:755 +0x25
crypto/tls.(*clientHandshakeState).handshake(0xc00103f450)
	crypto/tls/handshake_client.go:442 +0x35
crypto/tls.(*Conn).clientHandshake(0xc000694e08, {0x475baf8, 0xc00054b1d0})
	crypto/tls/handshake_client.go:274 +0x685
crypto/tls.(*Conn).handshakeContext(0xc000694e08, {0x475b8c8, 0x6d0e820})
	crypto/tls/conn.go:1553 +0x3cb
crypto/tls.(*Conn).HandshakeContext(...)
	crypto/tls/conn.go:1493
crypto/tls.(*Conn).Handshake(...)
	crypto/tls/conn.go:1477
crypto/tls.(*Conn).Write(0x30d31c0?, {0xc001002e40, 0x21, 0x40})
	crypto/tls/conn.go:1194 +0xe5
github.com/jackc/pgx/v5/pgproto3.(*Frontend).Flush(0xc0007ca008)
	github.com/jackc/pgx/v5@v5.5.3/pgproto3/frontend.go:88 +0x3d
github.com/jackc/pgx/v5/pgconn.(*PgConn).flushWithPotentialWriteReadDeadlock(0xc001230008)
	github.com/jackc/pgx/v5@v5.5.3/pgconn/pgconn.go:1818 +0x73
github.com/jackc/pgx/v5/pgconn.connect({0x475bb68, 0xc000020070}, 0xc0007ab680, 0xc000b2c160, 0x0)
	github.com/jackc/pgx/v5@v5.5.3/pgconn/pgconn.go:337 +0xbd3
github.com/jackc/pgx/v5/pgconn.ConnectConfig({0x475b8c8, 0x6d0e820}, 0xc0007ab680)
	github.com/jackc/pgx/v5@v5.5.3/pgconn/pgconn.go:176 +0x4f3
github.com/jackc/pgx/v5.connect({0x475b8c8?, 0x6d0e820?}, 0xc0007ab680)
	github.com/jackc/pgx/v5@v5.5.3/conn.go:257 +0x34b
github.com/jackc/pgx/v5.ConnectConfig({0x475b8c8, 0x6d0e820}, 0xc0007ab560)
	github.com/jackc/pgx/v5@v5.5.3/conn.go:141 +0xf0
github.com/jackc/pgx/v5/stdlib.(*driverConnector).Connect(0xc000fd6b28, {0x475b8c8, 0x6d0e820})
	github.com/jackc/pgx/v5@v5.5.3/stdlib/sql.go:365 +0xcd
database/sql.(*DB).conn(0xc000c7d790, {0x475b8c8, 0x6d0e820}, 0x1)
	database/sql/sql.go:1415 +0x71e
database/sql.(*DB).PingContext.func1(0xc8?)
	database/sql/sql.go:883 +0x3a
database/sql.(*DB).retry(0xc001087288?, 0xc001087258)
	database/sql/sql.go:1566 +0x42
database/sql.(*DB).PingContext(0xc000c7d790, {0x475b8c8, 0x6d0e820})
	database/sql/sql.go:882 +0x89
database/sql.(*DB).Ping(...)
	database/sql/sql.go:900
...

What did you expect to see?

Expected no segfault/panic. Looking at crypto/tls, it's my suspicion that, due to having goboring enabled and thus needing FIPS, tlsrsakex.Value() has not been called when tlsrsakex.IncNonDefault() is called. This could probably be triggered by having non default .CipherSuites set as well. Perhaps the underlying issue is that RSA ciphers aren't filtered out of fipsCipherSuites() in the first place, which is what allows the branch with IncNonDefault() to even be taken.
@seankhliao
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cc @golang/security

@FiloSottile
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The good news is that the IncNonDefault call is gated by hs.c.config.CipherSuites == nil, so it's not reachable by having non default CipherSuites.

Definitely an oversight in Go+BoringCrypto mode.

@FiloSottile
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@gopherbot please open a Go 1.22 backport issue. This is a severe regression in Go+BoringCrypto mode.

@gopherbot gopherbot mentioned this issue Feb 28, 2024
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@gopherbot
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Backport issue(s) opened: #65994 (for 1.22).

Remember to create the cherry-pick CL(s) as soon as the patch is submitted to master, according to https://go.dev/wiki/MinorReleases.

@slonka slonka mentioned this issue Feb 28, 2024
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5 tasks
@dmitshur dmitshur added this to the Go1.23 milestone Feb 28, 2024
@cagedmantis cagedmantis added the NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. label Feb 29, 2024
@brianstrauch brianstrauch mentioned this issue Mar 8, 2024
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@michaelbeaumont
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@FiloSottile Not sure who to ping on this, would it be enough to just solve the segfault and just stash the value of tlsrakex.Value() at the top of cipherSuites instead of after the first 2 function calls?

@bartsmykla bartsmykla mentioned this issue Apr 26, 2024
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@cagedmantis @FiloSottile @dmitshur @michaelbeaumont @gopherbot @seankhliao