Re: [PATCH-for-5.1] hw/ide/ahci: Do not dma_memory_unmap(NULL)
On 7/18/20 3:28 AM, Philippe Mathieu-Daudé wrote: libFuzzer triggered the following assertion: cat << EOF | qemu-system-i386 -M pc-q35-5.0 \ -nographic -monitor none -serial none -qtest stdio outl 0xcf8 0x8000fa24 outl 0xcfc 0xe1068000 outl 0xcf8 0x8000fa04 outw 0xcfc 0x7 outl 0xcf8 0x8000fb20 write 0xe1068304 0x1 0x21 write 0xe1068318 0x1 0x21 write 0xe1068384 0x1 0x21 write 0xe1068398 0x2 0x21 EOF qemu-system-i386: exec.c:3621: address_space_unmap: Assertion `mr != NULL' failed. Aborted (core dumped) This is because we don't check the return value from dma_memory_map() which can return NULL, then we call dma_memory_unmap(NULL) which is illegal. Fix by only unmap if the value is not NULL (and the size is not the expected one). Cc: qemu-sta...@nongnu.org Reported-by: Alexander Bulekov Fixes: f6ad2e32f8 ("ahci: add ahci emulation") BugLink: https://bugs.launchpad.net/qemu/+bug/1884693 Signed-off-by: Philippe Mathieu-Daudé --- hw/ide/ahci.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/hw/ide/ahci.c b/hw/ide/ahci.c index 009120f88b..4f596cb9ce 100644 --- a/hw/ide/ahci.c +++ b/hw/ide/ahci.c @@ -250,7 +250,7 @@ static void map_page(AddressSpace *as, uint8_t **ptr, uint64_t addr, } *ptr = dma_memory_map(as, addr, &len, DMA_DIRECTION_FROM_DEVICE); -if (len < wanted) { +if (len < wanted && *ptr) { dma_memory_unmap(as, *ptr, len, DMA_DIRECTION_FROM_DEVICE, len); *ptr = NULL; } Staged @ gitlab https://gitlab.com/jsnow/qemu/-/commits/ide
Re: [PATCH-for-5.1] hw/ide/ahci: Do not dma_memory_unmap(NULL)
On 7/18/20 3:28 AM, Philippe Mathieu-Daudé wrote: libFuzzer triggered the following assertion: cat << EOF | qemu-system-i386 -M pc-q35-5.0 \ -nographic -monitor none -serial none -qtest stdio outl 0xcf8 0x8000fa24 outl 0xcfc 0xe1068000 outl 0xcf8 0x8000fa04 outw 0xcfc 0x7 outl 0xcf8 0x8000fb20 write 0xe1068304 0x1 0x21 write 0xe1068318 0x1 0x21 write 0xe1068384 0x1 0x21 write 0xe1068398 0x2 0x21 EOF qemu-system-i386: exec.c:3621: address_space_unmap: Assertion `mr != NULL' failed. Aborted (core dumped) This is because we don't check the return value from dma_memory_map() which can return NULL, then we call dma_memory_unmap(NULL) which is illegal. Fix by only unmap if the value is not NULL (and the size is not the expected one). Cc: qemu-sta...@nongnu.org Reported-by: Alexander Bulekov Fixes: f6ad2e32f8 ("ahci: add ahci emulation") BugLink: https://bugs.launchpad.net/qemu/+bug/1884693 Signed-off-by: Philippe Mathieu-Daudé --- hw/ide/ahci.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/hw/ide/ahci.c b/hw/ide/ahci.c index 009120f88b..4f596cb9ce 100644 --- a/hw/ide/ahci.c +++ b/hw/ide/ahci.c @@ -250,7 +250,7 @@ static void map_page(AddressSpace *as, uint8_t **ptr, uint64_t addr, } *ptr = dma_memory_map(as, addr, &len, DMA_DIRECTION_FROM_DEVICE); -if (len < wanted) { +if (len < wanted && *ptr) { dma_memory_unmap(as, *ptr, len, DMA_DIRECTION_FROM_DEVICE, len); *ptr = NULL; } Reviewed-by: John Snow Thanks! this one wound up being easy.
Re: [PATCH-for-5.1] hw/ide/ahci: Do not dma_memory_unmap(NULL)
On 7/18/20 9:28 AM, Philippe Mathieu-Daudé wrote: > libFuzzer triggered the following assertion: > > cat << EOF | qemu-system-i386 -M pc-q35-5.0 \ > -nographic -monitor none -serial none -qtest stdio > outl 0xcf8 0x8000fa24 > outl 0xcfc 0xe1068000 > outl 0xcf8 0x8000fa04 > outw 0xcfc 0x7 > outl 0xcf8 0x8000fb20 > write 0xe1068304 0x1 0x21 > write 0xe1068318 0x1 0x21 > write 0xe1068384 0x1 0x21 > write 0xe1068398 0x2 0x21 > EOF > qemu-system-i386: exec.c:3621: address_space_unmap: Assertion `mr != NULL' > failed. > Aborted (core dumped) > > This is because we don't check the return value from dma_memory_map() > which can return NULL, then we call dma_memory_unmap(NULL) which is > illegal. Fix by only unmap if the value is not NULL (and the size is > not the expected one). Maybe worth mentioning it was hidden before but got revealed by commit 77f55eac6c ("exec: set map length to zero when returning NULL"). Cc'ing commit 77f55eac6c's reviewers. > Cc: qemu-sta...@nongnu.org > Reported-by: Alexander Bulekov > Fixes: f6ad2e32f8 ("ahci: add ahci emulation") > BugLink: https://bugs.launchpad.net/qemu/+bug/1884693 > Signed-off-by: Philippe Mathieu-Daudé > --- > hw/ide/ahci.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/hw/ide/ahci.c b/hw/ide/ahci.c > index 009120f88b..4f596cb9ce 100644 > --- a/hw/ide/ahci.c > +++ b/hw/ide/ahci.c > @@ -250,7 +250,7 @@ static void map_page(AddressSpace *as, uint8_t **ptr, > uint64_t addr, > } > > *ptr = dma_memory_map(as, addr, &len, DMA_DIRECTION_FROM_DEVICE); > -if (len < wanted) { > +if (len < wanted && *ptr) { > dma_memory_unmap(as, *ptr, len, DMA_DIRECTION_FROM_DEVICE, len); > *ptr = NULL; > } >
[PATCH-for-5.1] hw/ide/ahci: Do not dma_memory_unmap(NULL)
libFuzzer triggered the following assertion: cat << EOF | qemu-system-i386 -M pc-q35-5.0 \ -nographic -monitor none -serial none -qtest stdio outl 0xcf8 0x8000fa24 outl 0xcfc 0xe1068000 outl 0xcf8 0x8000fa04 outw 0xcfc 0x7 outl 0xcf8 0x8000fb20 write 0xe1068304 0x1 0x21 write 0xe1068318 0x1 0x21 write 0xe1068384 0x1 0x21 write 0xe1068398 0x2 0x21 EOF qemu-system-i386: exec.c:3621: address_space_unmap: Assertion `mr != NULL' failed. Aborted (core dumped) This is because we don't check the return value from dma_memory_map() which can return NULL, then we call dma_memory_unmap(NULL) which is illegal. Fix by only unmap if the value is not NULL (and the size is not the expected one). Cc: qemu-sta...@nongnu.org Reported-by: Alexander Bulekov Fixes: f6ad2e32f8 ("ahci: add ahci emulation") BugLink: https://bugs.launchpad.net/qemu/+bug/1884693 Signed-off-by: Philippe Mathieu-Daudé --- hw/ide/ahci.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/hw/ide/ahci.c b/hw/ide/ahci.c index 009120f88b..4f596cb9ce 100644 --- a/hw/ide/ahci.c +++ b/hw/ide/ahci.c @@ -250,7 +250,7 @@ static void map_page(AddressSpace *as, uint8_t **ptr, uint64_t addr, } *ptr = dma_memory_map(as, addr, &len, DMA_DIRECTION_FROM_DEVICE); -if (len < wanted) { +if (len < wanted && *ptr) { dma_memory_unmap(as, *ptr, len, DMA_DIRECTION_FROM_DEVICE, len); *ptr = NULL; } -- 2.21.3