65 lines
2.0 KiB
Diff
65 lines
2.0 KiB
Diff
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From bd78a5dfd47043db08982464bcae4759c0980975 Mon Sep 17 00:00:00 2001
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From: Jean Delvare <jdelvare@suse.de>
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Date: Wed, 1 Aug 2018 09:54:55 +0200
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Subject: [PATCH 21/21] dmidecode: Don't allocate more memory than needed
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If the actual DMI table size is less than the announced maximum
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(which is allowed for 64-bit SMBIOS 3 entry points), we may allocate
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significantly more memory than is actually needed. If reading from
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/dev/mem, there's nothing we can do about that. However, is reading
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from sysfs or from a dump file, we can easily check the file size
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and compute the actual table size from it. That way we only allocate
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the required amount of memory.
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Credits to Lionel Debroux for seeding the idea when performing fuzz
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testing on dmidecode.
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Signed-off-by: Jean Delvare <jdelvare@suse.de>
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---
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util.c | 15 ++++++++++++---
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1 file changed, 12 insertions(+), 3 deletions(-)
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diff --git a/util.c b/util.c
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index 0aafcb1..7049817 100644
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--- a/util.c
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+++ b/util.c
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@@ -90,16 +90,16 @@ int checksum(const u8 *buf, size_t len)
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/*
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* Reads all of file from given offset, up to max_len bytes.
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- * A buffer of max_len bytes is allocated by this function, and
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+ * A buffer of at most max_len bytes is allocated by this function, and
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* needs to be freed by the caller.
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* This provides a similar usage model to mem_chunk()
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*
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- * Returns pointer to buffer of max_len bytes, or NULL on error, and
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+ * Returns a pointer to the allocated buffer, or NULL on error, and
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* sets max_len to the length actually read.
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- *
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*/
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void *read_file(off_t base, size_t *max_len, const char *filename)
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{
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+ struct stat statbuf;
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int fd;
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size_t r2 = 0;
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ssize_t r;
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@@ -124,6 +124,15 @@ void *read_file(off_t base, size_t *max_len, const char *filename)
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goto out;
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}
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+ /*
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+ * Check file size, don't allocate more than can be read.
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+ */
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+ if (fstat(fd, &statbuf) == 0)
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+ {
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+ if (base + (off_t)*max_len > statbuf.st_size)
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+ *max_len = statbuf.st_size - base;
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+ }
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+
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if ((p = malloc(*max_len)) == NULL)
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{
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perror("malloc");
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--
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2.17.1
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