Thank you for your contribution! Sashiko AI review found 3 potential issue(s) to consider:
Pre-existing issues: - [High] Missing READ_ONCE on shared BO field `command_count` leaves it vulnerable to compiler refetching optimization. - [High] Memory leak of a GEM object reference on the error path in `amdxdna_cmd_set_error()`. - [Medium] Race condition where the error state is written to the command header before the error payload is populated. -- commit b8c13d2d8e5350b458948c5624a0d76772f2851a Author: Taimuraz Kaitmazov <[email protected]> accel/amdxdna: use READ_ONCE/WRITE_ONCE on the command header The driver modifies state flags in place, allowing the compiler to split or refetch accesses. This patch annotates these accesses with READ_ONCE and WRITE_ONCE to stop the compiler from optimizing them in unsafe ways. > diff --git a/drivers/accel/amdxdna/amdxdna_ctx.c > b/drivers/accel/amdxdna/amdxdna_ctx.c > index 143cbbbf4b310..f809bec425a57 100644 > --- a/drivers/accel/amdxdna/amdxdna_ctx.c > +++ b/drivers/accel/amdxdna/amdxdna_ctx.c [ ... ] > @@ -191,12 +192,15 @@ int amdxdna_cmd_set_error(struct amdxdna_gem_obj *abo, > struct amdxdna_client *client = job->hwctx->client; > struct amdxdna_cmd *cmd = amdxdna_gem_vmap(abo); > struct amdxdna_cmd_chain *cc = NULL; > + u32 header; > > if (!cmd) > return -ENOMEM; > > - cmd->header &= ~AMDXDNA_CMD_STATE; > - cmd->header |= FIELD_PREP(AMDXDNA_CMD_STATE, error_state); > + header = READ_ONCE(cmd->header); > + header &= ~AMDXDNA_CMD_STATE; > + header |= FIELD_PREP(AMDXDNA_CMD_STATE, error_state); > + WRITE_ONCE(cmd->header, header); [Severity: Medium] This is a pre-existing issue, but does writing the error state here create a race condition where user-space might read stale or garbage data? The driver modifies the state flags in the shared cmd->header prior to issuing the memset and memcpy to populate the error payload later in the function: memset(cmd->data, 0xff, abo->mem.size - sizeof(*cmd)); if (err_data) memcpy(cmd->data, err_data, min(size, abo->mem.size - sizeof(*cmd))); If user-space is polling the state field, could it see the error state and immediately read the payload before the driver has finished writing it? [Severity: High] This is also a pre-existing issue in this same function, but does this code leak a GEM object reference on the error path? If amdxdna_gem_vmap() fails after acquiring the abo reference, the code returns -ENOMEM without calling amdxdna_gem_put_obj(): if (amdxdna_cmd_get_op(abo) == ERT_CMD_CHAIN) { ... abo = amdxdna_gem_get_obj(client, cc->data[0], AMDXDNA_BO_SHARE); if (!abo) return -EINVAL; cmd = amdxdna_gem_vmap(abo); if (!cmd) return -ENOMEM; } Could successive failures eventually exhaust kernel memory resources? [Severity: High] This isn't a bug introduced by this patch, but while annotating BO memory accesses with READ_ONCE, are there other places where shared BO fields are read without it? For instance, command_count is read from shared memory and used in bounds checks in aie2_cmdlist_multi_execbuf(): ccnt = payload->command_count; if (payload_len < struct_size(payload, data, ccnt)) { ... for (i = 0; i < ccnt; i++) And similarly in amdxdna_cmd_get_chain(): ccnt = cc->command_count; if (len < struct_size(cc, data, ccnt)) Could the compiler refetch command_count from shared memory after the bounds check? If user space concurrently modifies the value after the bounds check, could the subsequent loop read out-of-bounds kernel memory, potentially leading to a kernel page fault? -- Sashiko AI review ยท https://sashiko.dev/#/patchset/[email protected]?part=2
