From a73c74db66a14540eb043bf9535c0d9c37804062 Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Thu, 22 Jun 2023 16:48:48 +0200
Subject: [PATCH 1/3] coredump: use loop_read() for reading coredump into
 memory

Fixes: #26748
---
 src/basic/io-util.c     |  3 +--
 src/coredump/coredump.c | 11 ++++++-----
 2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/src/basic/io-util.c b/src/basic/io-util.c
index 6f6fb8068c..bf1aab9e38 100644
--- a/src/basic/io-util.c
+++ b/src/basic/io-util.c
@@ -54,8 +54,7 @@ ssize_t loop_read(int fd, void *buf, size_t nbytes, bool do_poll) {
 
         assert(fd >= 0);
 
-        /* If called with nbytes == 0, let's call read() at least
-         * once, to validate the operation */
+        /* If called with nbytes == 0, let's call read() at least once, to validate the operation */
 
         if (nbytes > (size_t) SSIZE_MAX)
                 return -EINVAL;
diff --git a/src/coredump/coredump.c b/src/coredump/coredump.c
index 847ac531df..940c0def61 100644
--- a/src/coredump/coredump.c
+++ b/src/coredump/coredump.c
@@ -604,14 +604,15 @@ static int allocate_journal_field(int fd, size_t size, char **ret, size_t *ret_s
                 return log_warning_errno(errno, "Failed to seek: %m");
 
         field = malloc(9 + size);
-        if (!field) {
-                log_warning("Failed to allocate memory for coredump, coredump will not be stored.");
-                return -ENOMEM;
-        }
+        if (!field)
+                return log_warning_errno(SYNTHETIC_ERRNO(ENOMEM),
+                                         "Failed to allocate memory for coredump, coredump will not be stored.");
 
         memcpy(field, "COREDUMP=", 9);
 
-        n = read(fd, field + 9, size);
+        /* NB: simple read() would fail for overly large coredumps, since read() on Linux can only deal with
+         * 0x7ffff000 bytes max. Hence call things in a loop. */
+        n = loop_read(fd, field + 9, size, /* do_poll= */ false);
         if (n < 0)
                 return log_error_errno((int) n, "Failed to read core data: %m");
         if ((size_t) n < size)

From 4a78074fc14c684600f2bbdac7b5bb13325aba39 Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Thu, 22 Jun 2023 17:11:00 +0200
Subject: [PATCH 2/3] coredump: clamp JournalSizeMax= to maximum journald would
 accept

See: #26748
---
 src/coredump/coredump.c | 24 +++++++++++++++++++++---
 1 file changed, 21 insertions(+), 3 deletions(-)

diff --git a/src/coredump/coredump.c b/src/coredump/coredump.c
index 940c0def61..39b777b535 100644
--- a/src/coredump/coredump.c
+++ b/src/coredump/coredump.c
@@ -172,9 +172,27 @@ static int parse_config(void) {
                 {}
         };
 
-        return config_parse_config_file("coredump.conf", "Coredump\0",
-                                        config_item_table_lookup, items,
-                                        CONFIG_PARSE_WARN, NULL);
+        int r;
+
+        r = config_parse_config_file(
+                        "coredump.conf",
+                        "Coredump\0",
+                        config_item_table_lookup,
+                        items,
+                        CONFIG_PARSE_WARN,
+                        /* userdata= */ NULL);
+        if (r < 0)
+                return r;
+
+        /* Let's make sure we fix up the maximum size we send to the journal here on the client side, for
+         * efficiency reasons. journald wouldn't accept anything larger anyway. */
+        if (arg_journal_size_max > JOURNAL_SIZE_MAX) {
+                log_warning("JournalSizeMax= set to larger value (%s) than journald would accept (%s), lowering automatically.",
+                            FORMAT_BYTES(arg_journal_size_max), FORMAT_BYTES(JOURNAL_SIZE_MAX));
+                arg_journal_size_max = JOURNAL_SIZE_MAX;
+        }
+
+        return 0;
 }
 
 static uint64_t storage_size_max(void) {

From e6421b6ccd4677d22380d3f3dcb688ec9e347784 Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Thu, 22 Jun 2023 17:10:14 +0200
Subject: [PATCH 3/3] man: correct and extend JournalSizeMax=

The man page claimed the default was 10M, but that's not true, it's
767M.

Also mention there's no point in increasing it further.

See: #26748
---
 man/coredump.conf.xml | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/man/coredump.conf.xml b/man/coredump.conf.xml
index 7cb71f80aa..7a617b1985 100644
--- a/man/coredump.conf.xml
+++ b/man/coredump.conf.xml
@@ -97,11 +97,14 @@
         <term><varname>ExternalSizeMax=</varname></term>
         <term><varname>JournalSizeMax=</varname></term>
 
-        <listitem><para>The maximum (compressed or uncompressed) size in bytes of a core to be saved in
-        separate files on disk (default: 1G on 32bit, 32G on 64bit systems) or in the journal (default:
-        10M). Unit suffixes are allowed just as in <option>ProcessSizeMax=</option>.</para></listitem>
+        <listitem><para>The maximum (compressed or uncompressed) size in bytes of a coredump to be saved in
+        separate files on disk (default: 1G on 32-bit systems, 32G on 64-bit systems) or in the journal
+        (default: 767M). Note that the journal service enforces a hard limit on journal log records of 767M,
+        and will ignore larger submitted log records. Hence, <varname>JournalSizeMax=</varname> may be
+        lowered relative to the default, but not increased. Unit suffixes are allowed just as in
+        <option>ProcessSizeMax=</option>.</para>
 
-        <para><varname>ExternalSizeMax=infinity</varname> sets the core size to unlimited.</para>
+        <para><varname>ExternalSizeMax=infinity</varname> sets the core size to unlimited.</para></listitem>
       </varlistentry>
 
       <varlistentry>