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fix: validate NCCL_TESTS_SPLIT env vars and guard division by zero #379

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fix: validate NCCL_TESTS_SPLIT env vars and guard division by zero #379

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70001d1
test: add split env var safety tests for strtoul and div-by-zero (7 c…
randomizedcoder Apr 29, 2026
9fc4671
fix: validate NCCL_TESTS_SPLIT_MASK input and guard against division …
randomizedcoder Apr 29, 2026
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45 changes: 33 additions & 12 deletions src/common.cu
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Original file line number Diff line number Diff line change
Expand Up @@ -1229,12 +1229,16 @@ static bool parseInt(char *s, int *num) {
while (*s && isspace(*s)) ++s;
if (!*s) return false;

if (strncasecmp(s, "0b", 2) == 0)
*num = (int)strtoul(s + 2, &p, 2);
else
*num = (int)strtoul(s, &p, 0);
errno = 0;
char *start = s;
if (strncasecmp(s, "0b", 2) == 0) {
start = s + 2;
*num = (int)strtoul(start, &p, 2);
} else {
*num = (int)strtoul(start, &p, 0);
}

if (p == s)
if (p == start || errno == ERANGE)
return false;
return true;
}
Expand All @@ -1258,9 +1262,16 @@ testResult_t run() {
}

char *splitMaskEnv = NULL;
if (splitMaskEnv = getenv("NCCL_TESTS_SPLIT_MASK")) {
color = proc & strtoul(splitMaskEnv, NULL, 16);
} else if (splitMaskEnv = getenv("NCCL_TESTS_SPLIT")) {
if ((splitMaskEnv = getenv("NCCL_TESTS_SPLIT_MASK"))) {
char *end;
errno = 0;
unsigned long mask = strtoul(splitMaskEnv, &end, 16);
if (end == splitMaskEnv || *end != '\0' || errno == ERANGE) {
fprintf(stderr, "Warning: invalid NCCL_TESTS_SPLIT_MASK='%s', ignoring\n", splitMaskEnv);
} else {
color = proc & (int)mask;
}
} else if ((splitMaskEnv = getenv("NCCL_TESTS_SPLIT"))) {
if (
(strncasecmp(splitMaskEnv, "AND", strlen("AND")) == 0 && parseInt(splitMaskEnv + strlen("AND"), &color)) ||
(strncasecmp(splitMaskEnv, "&", strlen("&")) == 0 && parseInt(splitMaskEnv + strlen("&"), &color))
Expand All @@ -1274,13 +1285,23 @@ testResult_t run() {
if (
(strncasecmp(splitMaskEnv, "MOD", strlen("MOD")) == 0 && parseInt(splitMaskEnv + strlen("MOD"), &color)) ||
(strncasecmp(splitMaskEnv, "%", strlen("%")) == 0 && parseInt(splitMaskEnv + strlen("%"), &color))
)
color = proc % color;
) {
if (color == 0) {
fprintf(stderr, "Warning: NCCL_TESTS_SPLIT modulo by zero, ignoring\n");
} else {
color = proc % color;
}
}
if (
(strncasecmp(splitMaskEnv, "DIV", strlen("DIV")) == 0 && parseInt(splitMaskEnv + strlen("DIV"), &color)) ||
(strncasecmp(splitMaskEnv, "/", strlen("/")) == 0 && parseInt(splitMaskEnv + strlen("/"), &color))
)
color = proc / color;
) {
if (color == 0) {
fprintf(stderr, "Warning: NCCL_TESTS_SPLIT division by zero, ignoring\n");
} else {
color = proc / color;
}
}
}

MPI_Comm mpi_comm;
Expand Down
6 changes: 6 additions & 0 deletions tests/Makefile
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Original file line number Diff line number Diff line change
@@ -0,0 +1,6 @@
SUBDIRS := $(shell ls -d c 2>/dev/null)

test:
@for d in $(SUBDIRS); do $(MAKE) -C $$d test; done

.PHONY: test
19 changes: 19 additions & 0 deletions tests/c/Makefile
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Original file line number Diff line number Diff line change
@@ -0,0 +1,19 @@
CC := gcc
CFLAGS := -Wall -Wextra -Wno-format-truncation -g -std=c99 -fPIC -D_GNU_SOURCE
LDFLAGS := -lpthread

SOURCES := $(wildcard test_*.c)
TARGETS := $(SOURCES:.c=)

all: $(TARGETS)

%: %.c
$(CC) $(CFLAGS) -o $@ $< $(LDFLAGS)

test: $(TARGETS)
@for t in $(TARGETS); do echo "=== $$t ==="; ./$$t; echo; done

clean:
rm -f $(TARGETS)

.PHONY: all test clean
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