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| author | Daniel Henrique Barboza | 2022-01-28 13:15:02 +0100 |
|---|---|---|
| committer | Cédric Le Goater | 2022-01-28 13:15:02 +0100 |
| commit | 83d2bea68a778b98ecbf9472be6f1ed8031719ac (patch) | |
| tree | 5e72aac17b490517d1519e7131c30f28ed818390 /hw | |
| parent | ppc/pnv: Fail DMA access if page permissions are not correct (diff) | |
| download | qemu-83d2bea68a778b98ecbf9472be6f1ed8031719ac.tar.gz qemu-83d2bea68a778b98ecbf9472be6f1ed8031719ac.tar.xz qemu-83d2bea68a778b98ecbf9472be6f1ed8031719ac.zip | |
ppc/pnv: use a do-while() loop in pnv_phb3_translate_tve()
The 'taddr' variable is left unintialized, being set only inside the
"while ((lev--) >= 0)" loop where we get the TCE address. The 'lev' var
is an int32_t that is being initiliazed by the GETFIELD() macro, which
returns an uint64_t.
For a human reader this means that 'lev' will always be positive or zero.
But some compilers may beg to differ. 'lev' being an int32_t can in theory
be set as negative, and the "while ((lev--) >= 0)" loop might never be
reached, and 'taddr' will be left unitialized. This can cause phb3_error()
to use 'taddr' uninitialized down below:
if ((is_write & !(tce & 2)) || ((!is_write) && !(tce & 1))) {
phb3_error(phb, "TCE access fault at 0x%"PRIx64, taddr);
A quick way of fixing it is to use a do/while() loop. This will keep the
same semanting as the existing while() loop does and the compiler will
understand that 'taddr' will be initialized at least once.
Suggested-by: Matheus K. Ferst <matheus.ferst@eldorado.org.br>
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/573
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Message-Id: <20220127122234.842145-2-danielhb413@gmail.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Diffstat (limited to 'hw')
| -rw-r--r-- | hw/pci-host/pnv_phb3.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/hw/pci-host/pnv_phb3.c b/hw/pci-host/pnv_phb3.c index a757f1a58e..aafd46b635 100644 --- a/hw/pci-host/pnv_phb3.c +++ b/hw/pci-host/pnv_phb3.c @@ -792,7 +792,9 @@ static void pnv_phb3_translate_tve(PnvPhb3DMASpace *ds, hwaddr addr, sh = tbl_shift * lev + tce_shift; /* TODO: Multi-level untested */ - while ((lev--) >= 0) { + do { + lev--; + /* Grab the TCE address */ taddr = base | (((addr >> sh) & ((1ul << tbl_shift) - 1)) << 3); if (dma_memory_read(&address_space_memory, taddr, &tce, @@ -813,7 +815,7 @@ static void pnv_phb3_translate_tve(PnvPhb3DMASpace *ds, hwaddr addr, } sh -= tbl_shift; base = tce & ~0xfffull; - } + } while (lev >= 0); /* We exit the loop with TCE being the final TCE */ if ((is_write & !(tce & 2)) || ((!is_write) && !(tce & 1))) { |