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log: add upper bound to journal iovec accounting

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Use checked arithmetic before clamping the journal iovec length.
Stop copying input iovecs once the fixed journal vector is full.

Follow-up for e69cc9eb36
This commit is contained in:
Luca Boccassi
2026-07-14 16:43:28 +01:00
parent 66600e15c9
commit f5e35f72cf
2 changed files with 41 additions and 5 deletions
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src/basic/log.c
+19 -5
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@@ -726,7 +726,11 @@ static int write_to_journal(
if (LOG_PRI(level) > log_target_max_level[LOG_TARGET_JOURNAL])
return 0;
iovec_len = MIN(6 + log_context_num_fields() * 3, IOVEC_MAX);
if (!MUL_SAFE(&iovec_len, log_context_num_fields(), 3) ||
!ADD_SAFE(&iovec_len, iovec_len, 6))
iovec_len = IOVEC_MAX;
else
iovec_len = MIN(iovec_len, IOVEC_MAX);
iovec = newa(struct iovec, iovec_len);
log_do_header(header, sizeof(header), level, error, file, line, func, object_field, object, extra_field, extra);
@@ -1024,7 +1028,11 @@ int log_struct_internal(
int r;
bool fallback = false;
iovec_len = MIN(17 + log_context_num_fields() * 3, IOVEC_MAX);
if (!MUL_SAFE(&iovec_len, log_context_num_fields(), 3) ||
!ADD_SAFE(&iovec_len, iovec_len, 17))
iovec_len = IOVEC_MAX;
else
iovec_len = MIN(iovec_len, IOVEC_MAX);
iovec = newa(struct iovec, iovec_len);
/* If the journal is available do structured logging.
@@ -1123,15 +1131,21 @@ int log_struct_iovec_internal(
char header[LINE_MAX];
struct iovec *iovec;
size_t n = 0, iovec_len;
size_t n = 0, iovec_len, n_context_iovec, n_input_iovec_expanded;
iovec_len = MIN(1 + n_input_iovec * 2 + log_context_num_fields() * 3, IOVEC_MAX);
if (!MUL_SAFE(&n_input_iovec_expanded, n_input_iovec, 2) ||
!MUL_SAFE(&n_context_iovec, log_context_num_fields(), 3) ||
!ADD_SAFE(&iovec_len, 1, n_input_iovec_expanded) ||
!ADD_SAFE(&iovec_len, iovec_len, n_context_iovec))
iovec_len = IOVEC_MAX;
else
iovec_len = MIN(iovec_len, IOVEC_MAX);
iovec = newa(struct iovec, iovec_len);
log_do_header(header, sizeof(header), level, error, file, line, func, NULL, NULL, NULL, NULL);
iovec[n++] = IOVEC_MAKE_STRING(header);
for (size_t i = 0; i < n_input_iovec; i++) {
for (size_t i = 0; i < n_input_iovec && n + 2 <= iovec_len; i++) {
iovec[n++] = input_iovec[i];
iovec[n++] = IOVEC_MAKE_STRING("\n");
}