From 4ce1e15fbc7266a108a7c77a3962644b3935346e Mon Sep 17 00:00:00 2001 From: Christophe de Dinechin Date: Fri, 28 Feb 2020 16:00:59 +0100 Subject: [PATCH] scsi/qemu-pr-helper: Fix out-of-bounds access to trnptid_list[] MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Compile error reported by gcc 10.0.1: scsi/qemu-pr-helper.c: In function ‘multipath_pr_out’: scsi/qemu-pr-helper.c:523:32: error: array subscript is outside array bounds of ‘struct transportid *[0]’ [-Werror=array-bounds] 523 | paramp.trnptid_list[paramp.num_transportid++] = id; | ~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~ In file included from scsi/qemu-pr-helper.c:36: /usr/include/mpath_persist.h:168:22: note: while referencing ‘trnptid_list’ 168 | struct transportid *trnptid_list[]; | ^~~~~~~~~~~~ scsi/qemu-pr-helper.c:424:35: note: defined here ‘paramp’ 424 | struct prout_param_descriptor paramp; | ^~~~~~ This highlights an actual implementation issue in function multipath_pr_out. The variable paramp is declared with type `struct prout_param_descriptor`, which is a struct terminated by an empty array in mpath_persist.h: struct transportid *trnptid_list[]; That empty array was filled with code that looked like that: trnptid_list[paramp.descr.num_transportid++] = id; This is an actual out-of-bounds access. The fix is to malloc `paramp`. Signed-off-by: Christophe de Dinechin Signed-off-by: Paolo Bonzini --- scsi/qemu-pr-helper.c | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-) diff --git a/scsi/qemu-pr-helper.c b/scsi/qemu-pr-helper.c index 0659ceef09..181ed4a186 100644 --- a/scsi/qemu-pr-helper.c +++ b/scsi/qemu-pr-helper.c @@ -421,10 +421,13 @@ static int multipath_pr_out(int fd, const uint8_t *cdb, uint8_t *sense, int rq_servact = cdb[1]; int rq_scope = cdb[2] >> 4; int rq_type = cdb[2] & 0xf; - struct prout_param_descriptor paramp; + g_autofree struct prout_param_descriptor *paramp = NULL; char transportids[PR_HELPER_DATA_SIZE]; int r; + paramp = g_malloc0(sizeof(struct prout_param_descriptor) + + sizeof(struct transportid *) * MPATH_MX_TIDS); + if (sz < PR_OUT_FIXED_PARAM_SIZE) { /* Illegal request, Parameter list length error. This isn't fatal; * we have read the data, send an error without closing the socket. @@ -454,10 +457,9 @@ static int multipath_pr_out(int fd, const uint8_t *cdb, uint8_t *sense, * used by libmpathpersist (which, of course, will immediately * do the opposite). */ - memset(¶mp, 0, sizeof(paramp)); - memcpy(¶mp.key, ¶m[0], 8); - memcpy(¶mp.sa_key, ¶m[8], 8); - paramp.sa_flags = param[20]; + memcpy(¶mp->key, ¶m[0], 8); + memcpy(¶mp->sa_key, ¶m[8], 8); + paramp->sa_flags = param[20]; if (sz > PR_OUT_FIXED_PARAM_SIZE) { size_t transportid_len; int i, j; @@ -520,12 +522,13 @@ static int multipath_pr_out(int fd, const uint8_t *cdb, uint8_t *sense, return CHECK_CONDITION; } - paramp.trnptid_list[paramp.num_transportid++] = id; + assert(paramp->num_transportid < MPATH_MX_TIDS); + paramp->trnptid_list[paramp->num_transportid++] = id; } } r = mpath_persistent_reserve_out(fd, rq_servact, rq_scope, rq_type, - ¶mp, noisy, verbose); + paramp, noisy, verbose); return mpath_reconstruct_sense(fd, r, sense); } #endif