oomd: review follow ups to #20020

(cherry picked from commit e82acab4db6f5f212f6c9c9b3ec2df9010a83925)

3 files changed, 27 insertions, 12 deletions

diff --git a/src/basic/procfs-util.c b/src/basic/procfs-util.c
index db3e29d04a..9234ccaf85 100644
--- a/src/basic/procfs-util.c
+++ b/src/basic/procfs-util.c
@@ -201,7 +201,8 @@ int procfs_cpu_get_usage(nsec_t *ret) {
         return 0;
 }
 
-int convert_meminfo_value_to_uint64_bytes(char *word, uint64_t *ret) {
+int convert_meminfo_value_to_uint64_bytes(const char *word, uint64_t *ret) {
+        _cleanup_free_ char *w = NULL;
         char *digits, *e;
         uint64_t v;
         size_t n;
@@ -210,9 +211,13 @@ int convert_meminfo_value_to_uint64_bytes(char *word, uint64_t *ret) {
         assert(word);
         assert(ret);
 
+        w = strdup(word);
+        if (!w)
+                return -ENOMEM;
+
         /* Determine length of numeric value */
-        n = strspn(word, WHITESPACE);
-        digits = word + n;
+        n = strspn(w, WHITESPACE);
+        digits = w + n;
         n = strspn(digits, DIGITS);
         if (n == 0)
                 return -EINVAL;
@@ -232,6 +237,9 @@ int convert_meminfo_value_to_uint64_bytes(char *word, uint64_t *ret) {
         if (v == UINT64_MAX)
                 return -EINVAL;
 
+        if (v > UINT64_MAX/1024)
+                return -EOVERFLOW;
+
         *ret = v * 1024U;
         return 0;
 }
diff --git a/src/basic/procfs-util.h b/src/basic/procfs-util.h
index b7bf7b729d..61fa71d479 100644
--- a/src/basic/procfs-util.h
+++ b/src/basic/procfs-util.h
@@ -16,5 +16,4 @@ static inline int procfs_memory_get_used(uint64_t *ret) {
         return procfs_memory_get(NULL, ret);
 }
 
-/* This function destroys "word" (it'll be truncated to perform conversion) */
-int convert_meminfo_value_to_uint64_bytes(char *word, uint64_t *ret);
+int convert_meminfo_value_to_uint64_bytes(const char *word, uint64_t *ret);
diff --git a/src/oom/oomd-util.c b/src/oom/oomd-util.c
index f49cbe8e81..2ee81ce114 100644
--- a/src/oom/oomd-util.c
+++ b/src/oom/oomd-util.c
@@ -129,7 +129,7 @@ bool oomd_mem_free_below(const OomdSystemContext *ctx, int threshold_permyriad)
         assert(threshold_permyriad <= 10000);
 
         mem_threshold = ctx->mem_total * threshold_permyriad / (uint64_t) 10000;
-        return (ctx->mem_total - ctx->mem_used) < mem_threshold;
+        return LESS_BY(ctx->mem_total, ctx->mem_used) < mem_threshold;
 }
 
 bool oomd_swap_free_below(const OomdSystemContext *ctx, int threshold_permyriad) {
@@ -371,6 +371,14 @@ int oomd_system_context_acquire(const char *proc_meminfo_path, OomdSystemContext
         uint64_t mem_free, swap_free;
         int r;
 
+        enum {
+                MEM_TOTAL = 1U << 0,
+                MEM_FREE = 1U << 1,
+                SWAP_TOTAL = 1U << 2,
+                SWAP_FREE = 1U << 3,
+                ALL = MEM_TOTAL|MEM_FREE|SWAP_TOTAL|SWAP_FREE,
+        };
+
         assert(proc_meminfo_path);
         assert(ret);
 
@@ -389,16 +397,16 @@ int oomd_system_context_acquire(const char *proc_meminfo_path, OomdSystemContext
                         return -EINVAL;
 
                 if ((word = startswith(line, "MemTotal:"))) {
-                        field_filled |= 1U << 0;
+                        field_filled |= MEM_TOTAL;
                         r = convert_meminfo_value_to_uint64_bytes(word, &ctx.mem_total);
                 } else if ((word = startswith(line, "MemFree:"))) {
-                        field_filled |= 1U << 1;
+                        field_filled |= MEM_FREE;
                         r = convert_meminfo_value_to_uint64_bytes(word, &mem_free);
                 } else if ((word = startswith(line, "SwapTotal:"))) {
-                        field_filled |= 1U << 2;
+                        field_filled |= SWAP_TOTAL;
                         r = convert_meminfo_value_to_uint64_bytes(word, &ctx.swap_total);
                 } else if ((word = startswith(line, "SwapFree:"))) {
-                        field_filled |= 1U << 3;
+                        field_filled |= SWAP_FREE;
                         r = convert_meminfo_value_to_uint64_bytes(word, &swap_free);
                 } else
                         continue;
@@ -406,11 +414,11 @@ int oomd_system_context_acquire(const char *proc_meminfo_path, OomdSystemContext
                 if (r < 0)
                         return log_debug_errno(r, "Error converting '%s' from %s to uint64_t: %m", line, proc_meminfo_path);
 
-                if (field_filled == 15U)
+                if (field_filled == ALL)
                         break;
         }
 
-        if (field_filled != 15U)
+        if (field_filled != ALL)
                 return log_debug_errno(SYNTHETIC_ERRNO(EINVAL), "%s is missing expected fields", proc_meminfo_path);
 
         if (mem_free > ctx.mem_total)