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Integer overflow observed while formatting volume

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While calculating volume size, get_block_device_size() returns
u64 value but the returned value is assigned in ssize_t variable.
This may cause integer overflow if the volume size is beyond
ssize_t limit.

Use int64_t instead of ssize_t in get_file_size() and explicitly check
for overflow to fix the issue.

Bug: 65001754
Test: mmma bootable/recovery
Change-Id: I91eb30bff0bf7dcc48678efc2f414d2b79af6d0d
This commit is contained in:
Abhishek Arpure
2017-08-24 15:27:16 +05:30
committed by Tao Bao
parent fc570c317b
commit 4fec8e9e9a
1 changed files with 12 additions and 5 deletions
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roots.cpp
+12 -5
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@@ -18,6 +18,7 @@
#include <ctype.h>
#include <fcntl.h>
#include <stdint.h>
#include <stdlib.h>
#include <sys/mount.h>
#include <sys/stat.h>
@@ -178,16 +179,22 @@ static int exec_cmd(const std::vector<std::string>& args) {
return WEXITSTATUS(status);
}
static ssize_t get_file_size(int fd, uint64_t reserve_len) {
static int64_t get_file_size(int fd, uint64_t reserve_len) {
struct stat buf;
int ret = fstat(fd, &buf);
if (ret) return 0;
ssize_t computed_size;
int64_t computed_size;
if (S_ISREG(buf.st_mode)) {
computed_size = buf.st_size - reserve_len;
} else if (S_ISBLK(buf.st_mode)) {
computed_size = get_block_device_size(fd) - reserve_len;
uint64_t block_device_size = get_block_device_size(fd);
if (block_device_size < reserve_len ||
block_device_size > std::numeric_limits<int64_t>::max()) {
computed_size = 0;
} else {
computed_size = block_device_size - reserve_len;
}
} else {
computed_size = 0;
}
@@ -231,13 +238,13 @@ int format_volume(const char* volume, const char* directory) {
close(fd);
}
ssize_t length = 0;
int64_t length = 0;
if (v->length != 0) {
length = v->length;
} else if (v->key_loc != nullptr && strcmp(v->key_loc, "footer") == 0) {
android::base::unique_fd fd(open(v->blk_device, O_RDONLY));
if (fd == -1) {
PLOG(ERROR) << "get_file_size: failed to open " << v->blk_device;
PLOG(ERROR) << "format_volume: failed to open " << v->blk_device;
return -1;
}
length = get_file_size(fd.get(), CRYPT_FOOTER_OFFSET);