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[PATCH v4 31/53] semihosting: Bound length for semihost_sys_{read, write
From: |
Richard Henderson |
Subject: |
[PATCH v4 31/53] semihosting: Bound length for semihost_sys_{read, write} |
Date: |
Tue, 7 Jun 2022 13:45:35 -0700 |
Fixes a minor bug in which a 64-bit guest on a 32-bit host could
truncate the length. This would only ever cause a problem if
there were no bits set in the low 32, so that it truncates to 0.
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
semihosting/syscalls.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/semihosting/syscalls.c b/semihosting/syscalls.c
index 5cb12d6adc..eefbae74f1 100644
--- a/semihosting/syscalls.c
+++ b/semihosting/syscalls.c
@@ -283,6 +283,14 @@ void semihost_sys_close(CPUState *cs,
gdb_syscall_complete_cb complete, int fd)
void semihost_sys_read_gf(CPUState *cs, gdb_syscall_complete_cb complete,
GuestFD *gf, target_ulong buf, target_ulong len)
{
+ /*
+ * Bound length for 64-bit guests on 32-bit hosts, not overlowing ssize_t.
+ * Note the Linux kernel does this with MAX_RW_COUNT, so it's not a bad
+ * idea to do this unconditionally.
+ */
+ if (len > INT32_MAX) {
+ len = INT32_MAX;
+ }
switch (gf->type) {
case GuestFDGDB:
gdb_read(cs, complete, gf, buf, len);
@@ -313,6 +321,14 @@ void semihost_sys_read(CPUState *cs,
gdb_syscall_complete_cb complete,
void semihost_sys_write_gf(CPUState *cs, gdb_syscall_complete_cb complete,
GuestFD *gf, target_ulong buf, target_ulong len)
{
+ /*
+ * Bound length for 64-bit guests on 32-bit hosts, not overlowing ssize_t.
+ * Note the Linux kernel does this with MAX_RW_COUNT, so it's not a bad
+ * idea to do this unconditionally.
+ */
+ if (len > INT32_MAX) {
+ len = INT32_MAX;
+ }
switch (gf->type) {
case GuestFDGDB:
gdb_write(cs, complete, gf, buf, len);
--
2.34.1
- [PATCH v4 14/53] semihosting: Move common-semi.h to include/semihosting/, (continued)
- [PATCH v4 14/53] semihosting: Move common-semi.h to include/semihosting/, Richard Henderson, 2022/06/07
- [PATCH v4 16/53] include/exec: Move gdb open flags to gdbstub.h, Richard Henderson, 2022/06/07
- [PATCH v4 23/53] semihosting: Split out common_semi_has_synccache, Richard Henderson, 2022/06/07
- [PATCH v4 25/53] semihosting: Use env more often in do_common_semihosting, Richard Henderson, 2022/06/07
- [PATCH v4 27/53] semihosting: Split out semihost_sys_open, Richard Henderson, 2022/06/07
- [PATCH v4 31/53] semihosting: Bound length for semihost_sys_{read, write},
Richard Henderson <=
- [PATCH v4 35/53] semihosting: Split out semihost_sys_remove, Richard Henderson, 2022/06/07
- [PATCH v4 37/53] semihosting: Split out semihost_sys_system, Richard Henderson, 2022/06/07
- [PATCH v4 38/53] semihosting: Create semihost_sys_{stat,fstat}, Richard Henderson, 2022/06/07
- [PATCH v4 19/53] gdbstub: Convert GDB error numbers to host error numbers, Richard Henderson, 2022/06/07